Fix a build error when compiling with clang

Check __clang__ before __GNUC__ as clang defines both.

Change-Id: I9963f8e0665efb4cb08bd3886fb38fee42dd9861


[ROCm/ROCR-Runtime commit: 19e1fb3a4e]

projects/rocr-runtime/runtime/hsa-runtime/loader/executable.cpp

@@ -62,9 +62,7 @@
 using namespace amd::hsa;
 using namespace amd::hsa::common;
 
-#ifdef __GNUC__
-#define NONOPTIMIZE __attribute__((noinline, optimize(0)))
-#elif defined __clang__
+#if defined __clang__
 #define NONOPTIMIZE __attribute__((noinline, optnone))
 #else
 #define NONOPTIMIZE __attribute__((noinline, optimize(0)))