Don't build Macsyma if environment variable MACSYMA is no.

Use this to shorten the build times of the KLH10 and KA10 emulators.

.travis.yml

@@ -3,8 +3,8 @@ dist: trusty
 sudo: required
 env:
   - EMULATOR=simh
-  - EMULATOR=klh10
-  # EMULATOR=sims
+  - EMULATOR=klh10 MACSYMA=no
+  - EMULATOR=sims MACSYMA=no
 install: sh -ex build/dependencies.sh install_${TRAVIS_OS_NAME:-linux}
 script: make
 notifications:

build/build.tcl

@@ -1,3 +1,7 @@
+if {![info exists env(MACSYMA)]} {
+    set env(MACSYMA) "yes"
+}
+
 proc abort {} {
     puts ""
     puts "The last command timed out."
@@ -1584,6 +1588,8 @@ respond "_" "libmax;mdefun\r"
 respond "_" "\032"
 type ":kill\r"
 
+if {$env(MACSYMA)!="no"} {
+
 # build MAXTUL FASL files
 
 respond "*" ":print maxerr;..new. (udir)\r"
@@ -1779,6 +1785,8 @@ respond "(C1)" "quit();"
 
 respond "*" ":link sys3;ts macsym,maxdmp;loser >\r"
 
+} #MACSYMA
+
 ### more lisplib stuff
 respond "*" "complr\013"
 respond "_" "liblsp;_libdoc;%print\r"