cmake: don't check for the compiler on every invocation of RESTRICT_SYMBOL_EXPORTS(),

do it only once

cmake/libutils.cmake

@@ -304,23 +304,22 @@ FUNCTION(GET_DEPENDEND_OS_LIBS target result)
   SET(${result} ${ret} PARENT_SCOPE)
 ENDFUNCTION()
 
-# We try to hide the symbols in yassl/zlib to avoid name clashes with
-# other libraries like openssl.
-FUNCTION(RESTRICT_SYMBOL_EXPORTS target)
-  SET(VISIBILITY_HIDDEN_FLAG)
+SET(VISIBILITY_HIDDEN_FLAG)
 
-  IF(CMAKE_COMPILER_IS_GNUCXX AND UNIX)
-    CHECK_C_COMPILER_FLAG("-fvisibility=hidden" HAVE_VISIBILITY_HIDDEN)
-    IF(HAVE_VISIBILITY_HIDDEN)
-      MESSAGE(STATUS "HAVE_VISIBILITY_HIDDEN")
-      SET(VISIBILITY_HIDDEN_FLAG "-fvisibility=hidden")
-    ENDIF()
+IF(CMAKE_COMPILER_IS_GNUCXX AND UNIX)
+  CHECK_C_COMPILER_FLAG("-fvisibility=hidden" HAVE_VISIBILITY_HIDDEN)
+  IF(HAVE_VISIBILITY_HIDDEN)
+    SET(VISIBILITY_HIDDEN_FLAG "-fvisibility=hidden")
   ENDIF()
+ENDIF()
 
-  IF(CMAKE_C_COMPILER_ID MATCHES "SunPro")
-    SET(VISIBILITY_HIDDEN_FLAG "-xldscope=hidden")
-  ENDIF()
+IF(CMAKE_C_COMPILER_ID MATCHES "SunPro")
+  SET(VISIBILITY_HIDDEN_FLAG "-xldscope=hidden")
+ENDIF()
 
+# We try to hide the symbols in yassl/zlib to avoid name clashes with
+# other libraries like openssl.
+FUNCTION(RESTRICT_SYMBOL_EXPORTS target)
   IF(VISIBILITY_HIDDEN_FLAG)
     GET_TARGET_PROPERTY(COMPILE_FLAGS ${target} COMPILE_FLAGS)
     IF(NOT COMPILE_FLAGS)