KWIML: Avoid if() quoted auto-dereference

When testing CMAKE_<LANG>_COMPILER_ID values with if(STREQUAL), do not
explicitly dereference or quote the variable.  We want if() to
auto-dereference the variable and not its value.

test/CMakeLists.txt

@@ -20,7 +20,7 @@ set_property(DIRECTORY
 
 # Suppress printf/scanf format warnings; we test if the sizes match.
 foreach(lang C CXX)
-  if(KWIML_LANGUAGE_${lang} AND "${CMAKE_${lang}_COMPILER_ID}" STREQUAL GNU)
+  if(KWIML_LANGUAGE_${lang} AND CMAKE_${lang}_COMPILER_ID STREQUAL "GNU")
     set(CMAKE_${lang}_FLAGS "${CMAKE_${lang}_FLAGS} -Wno-format")
   endif()
 endforeach()