CMake: Updates

Issue #294: "apple silicon build problem(s?)": If the "--flavor/-f" flag
is not specified on the command line, then complain loudly, print help
and exit. The script used to default to "Unix Makefiles".

Updates:

- Add missing "-DHAVE_LIBPNG" compiler command line define when the PNG
  library is detected/present for screen capture support.

- Add "clang64" to the list of MinGW64 platforms for which the
  .travis/deps.sh script can install build dependencies.

- Add PThread4W_FOUND to the condition that sets async I/O for Win32
  when using vcpkg for build dependencies.

- Add vs2022-x64, vs2019-x64 and vs2017-x64 build environments to
  build 64-bit Windows executables.

- Use simulator AIO only where needed by the simulator (i.e., the
  simulator calls/uses AIO_CHECK_EVENT in sim_instr())

  - Add "USES_AIO" flag to add_simulator() to mark a simulator that
    acutally uses asynchronous I/O.

  - Build "_aio" SIMH core library variants that have AIO turned on,
    link with the "_aio" variant when a simulator sets USES_AIO.

  - Emit a warning message when WITH_ASYNC is False (CMake configuration
    option) to notify the user/developer that some functionality will be
    crippled.

  Affected simulator builds: 3b2 family, PDP-6, PDP-11, VAX family,
  IMLAC and TT2500. The makefile and cmake/generate.py also updated
  to remain in sync with CMake.

  N.B.: Simulators still link with the underlying platform's threading
  library. SEL32 requires pthreads or equivalent threading library,
  independent of AIO.

- cmake/cmake-builder.sh

  - New "--no-aio" flag: Build simulators without async I/O.

  - New "--no-aio-intrinsics" flag: Don't build async I/O using compiler
    compare-exchange, atomic load intrinsics.

- cmake/cmake-builder.ps1

  - New "-noaio" flag: Build simulators without async I/O.

  - New "-noaiointrinsics" flag: Don't build async I/O using compiler
    compare-exchange, atomic load intrinsics.

CMake 3.28.1 INTERFACE_LINK_LIBRARIES behavior change: The file name
must now be an absolute path. Relative paths no longer accepted.
Internally, SIMH enforces this if CMAKE_VERSION >= 3.19, when REAL_PATH
was first implemented.

VAX/CMakeLists.txt

@@ -140,6 +140,7 @@ add_simulator(infoserver100
         VAX_411
     FEATURE_FULL64
     FEATURE_VIDEO
+    USES_AIO
     BUILDROMS
     LABEL VAX
     PKG_FAMILY vax_family
@@ -169,6 +170,7 @@ add_simulator(infoserver1000
         VM_VAX
         IS_1000
     FEATURE_FULL64
+    USES_AIO
     BUILDROMS
     LABEL VAX
     PKG_FAMILY vax_family
@@ -186,6 +188,7 @@ add_simulator(infoserver150vxt
         VAX_412
     FEATURE_FULL64
     FEATURE_VIDEO
+    USES_AIO
     BUILDROMS
     LABEL VAX
     PKG_FAMILY vax_family
@@ -230,6 +233,7 @@ add_simulator(microvax1
         VAX_610
     FEATURE_FULL64
     FEATURE_VIDEO
+    USES_AIO
     BUILDROMS
     LABEL VAX
     PKG_FAMILY vax_family
@@ -246,6 +250,7 @@ add_simulator(microvax2
         VAX_630
     FEATURE_FULL64
     FEATURE_VIDEO
+    USES_AIO
     BUILDROMS
     LABEL VAX
     PKG_FAMILY vax_family
@@ -283,6 +288,7 @@ add_simulator(microvax2000
         VAX_410
     FEATURE_FULL64
     FEATURE_VIDEO
+    USES_AIO
     BUILDROMS
     LABEL VAX
     PKG_FAMILY vax_family
@@ -300,6 +306,7 @@ add_simulator(microvax3100
         VAX_41A
     FEATURE_FULL64
     FEATURE_VIDEO
+    USES_AIO
     BUILDROMS
     LABEL VAX
     PKG_FAMILY vax_family
@@ -317,6 +324,7 @@ add_simulator(microvax3100e
         VAX_41D
     FEATURE_FULL64
     FEATURE_VIDEO
+    USES_AIO
     BUILDROMS
     LABEL VAX
     PKG_FAMILY vax_family
@@ -332,6 +340,7 @@ add_simulator(microvax3100m80
         VAX_440
         VAX_47
     FEATURE_FULL64
+    USES_AIO
     BUILDROMS
     LABEL VAX
     PKG_FAMILY vax_family
@@ -362,6 +371,7 @@ add_simulator(vax
         VM_VAX
     FEATURE_FULL64
     FEATURE_VIDEO
+    USES_AIO
     BUILDROMS
     LABEL VAX
     PKG_FAMILY vax_family
@@ -435,6 +445,7 @@ add_simulator(vax730
         VM_VAX
         VAX_730
     FEATURE_FULL64
+    USES_AIO
     BUILDROMS
     LABEL VAX
     PKG_FAMILY vax_family
@@ -485,6 +496,7 @@ add_simulator(vax750
         VM_VAX
         VAX_750
     FEATURE_FULL64
+    USES_AIO
     BUILDROMS
     LABEL VAX
     PKG_FAMILY vax_family
@@ -536,6 +548,7 @@ add_simulator(vax780
         VM_VAX
         VAX_780
     FEATURE_FULL64
+    USES_AIO
     BUILDROMS
     LABEL VAX
     PKG_FAMILY vax_family
@@ -584,6 +597,7 @@ add_simulator(vax8200
         VM_VAX
         VAX_820
     FEATURE_FULL64
+    USES_AIO
     BUILDROMS
     LABEL VAX
     PKG_FAMILY vax_family
@@ -633,6 +647,7 @@ add_simulator(vax8600
         VM_VAX
         VAX_860
     FEATURE_FULL64
+    USES_AIO
     BUILDROMS
     LABEL VAX
     PKG_FAMILY vax_family
@@ -650,6 +665,7 @@ add_simulator(vaxstation3100m30
         VAX_42A
     FEATURE_FULL64
     FEATURE_VIDEO
+    USES_AIO
     BUILDROMS
     LABEL VAX
     PKG_FAMILY vax_family
@@ -667,6 +683,7 @@ add_simulator(vaxstation3100m38
         VAX_42B
     FEATURE_FULL64
     FEATURE_VIDEO
+    USES_AIO
     BUILDROMS
     LABEL VAX
     PKG_FAMILY vax_family
@@ -702,6 +719,7 @@ add_simulator(vaxstation3100m76
         VAX_43
     FEATURE_FULL64
     FEATURE_VIDEO
+    USES_AIO
     BUILDROMS
     LABEL VAX
     PKG_FAMILY vax_family
@@ -717,6 +735,7 @@ add_simulator(vaxstation4000m60
         VAX_440
         VAX_46
     FEATURE_FULL64
+    USES_AIO
     BUILDROMS
     LABEL VAX
     PKG_FAMILY vax_family
@@ -732,6 +751,7 @@ add_simulator(vaxstation4000vlc
         VAX_440
         VAX_48
     FEATURE_FULL64
+    USES_AIO
     BUILDROMS
     LABEL VAX
     PKG_FAMILY vax_family