GHS: Factor out compiler information shared among languages

Move common information in `Modules/Compiler/GHS-*.cmake` over to a
common `Modules/Compiler/GHS.cmake` and include it.

Modules/Compiler/GHS-C.cmake

@@ -1,3 +1,5 @@
+include(Compiler/GHS)
+
 set(CMAKE_C_VERBOSE_FLAG "-v")
 
 set(CMAKE_C_FLAGS_INIT "")
@@ -12,8 +14,6 @@ set(CMAKE_C_GHS_KERNEL_FLAGS_RELEASE_INIT "${CMAKE_C_FLAGS_RELEASE_INIT}")
 set(CMAKE_C_GHS_KERNEL_FLAGS_RELWITHDEBINFO_INIT
   "-ldebug ${CMAKE_C_FLAGS_RELWITHDEBINFO_INIT}")
 
-set(CMAKE_EXECUTABLE_SUFFIX ".as")
-
 if(NOT CMAKE_NOT_USING_CONFIG_FLAGS)
   set (CMAKE_C_GHS_KERNEL_FLAGS_DEBUG "${CMAKE_C_GHS_KERNEL_FLAGS_DEBUG_INIT}"
     CACHE STRING "Kernel flags used by the compiler during debug builds.")

Modules/Compiler/GHS-CXX.cmake

@@ -1,3 +1,5 @@
+include(Compiler/GHS)
+
 set(CMAKE_CXX_VERBOSE_FLAG "-v")
 
 set(CMAKE_CXX_FLAGS_INIT "")
@@ -15,8 +17,6 @@ set(CMAKE_CXX_GHS_KERNEL_FLAGS_RELEASE_INIT
 set(CMAKE_CXX_GHS_KERNEL_FLAGS_RELWITHDEBINFO_INIT
   "-ldebug ${CMAKE_CXX_FLAGS_RELWITHDEBINFO_INIT}")
 
-set(CMAKE_EXECUTABLE_SUFFIX ".as")
-
 if(NOT CMAKE_NOT_USING_CONFIG_FLAGS)
   set (CMAKE_CXX_GHS_KERNEL_FLAGS_DEBUG
     "${CMAKE_CXX_GHS_KERNEL_FLAGS_DEBUG_INIT}"

Modules/Compiler/GHS.cmake

@@ -0,0 +1,6 @@
+if(__COMPILER_GHS)
+  return()
+endif()
+set(__COMPILER_GHS 1)
+
+set(CMAKE_EXECUTABLE_SUFFIX ".as")