Make weak symbol usage more portable:

- Enable support for Green Hills Software compiler
- Define weak implementations only once except on Windows

auto/generate_test_runner.rb

@@ -158,7 +158,9 @@ class UnityTestRunnerGenerator
     create_runtest(output, mocks)
     output.puts("\n/*=======Automagically Detected Files To Include=====*/")
     output.puts("#include \"#{@options[:framework]}.h\"")
+    output.puts('#ifdef __WIN32__')
     output.puts("#include \"#{@options[:framework]}_setup.h\"")
+    output.puts('#endif')
     output.puts('#include "cmock.h"') unless mocks.empty?
     output.puts('#include <setjmp.h>')
     output.puts('#include <stdio.h>')

src/unity_internals.h

@@ -301,7 +301,7 @@ extern void UNITY_OMIT_OUTPUT_FLUSH_HEADER_DECLARATION;
  * Language Features Available
  *-------------------------------------------------------*/
 #if !defined(UNITY_WEAK_ATTRIBUTE) && !defined(UNITY_WEAK_PRAGMA)
-#   ifdef __GNUC__ /* includes clang */
+#   if defined(__GNUC__) || defined(__ghs__) /* __GNUC__ includes clang */
 #       if !(defined(__WIN32__) && defined(__clang__)) && !defined(__TMS470__)
 #           define UNITY_WEAK_ATTRIBUTE __attribute__((weak))
 #       endif