Don't use clang diagnostic pragma's when compiling with ICC on OSX.

The ICC frontend on OSX is clang, and therefore the "__clang__" define exists,
but it doesn't support the clang diagnostic pragma syntax.

Change-Id: I6947bd22c77af8066b85a6b00be7cf6019e7d06e

MD5.c

@@ -29,7 +29,7 @@
    it in a single source file instead of a separate header and
    implementation file.  */
 
-#if defined(__clang__)
+#if defined(__clang__) && !defined(__INTEL_COMPILER)
 # pragma clang diagnostic push
 # pragma clang diagnostic ignored "-Wcast-align"
 #endif
@@ -433,7 +433,7 @@ static void md5_finish(md5_state_t *pms, md5_byte_t digest[16])
         digest[i] = (md5_byte_t)(pms->abcd[i >> 2] >> ((i & 3) << 3));
 }
 
-#if defined(__clang__)
+#if defined(__clang__) && !defined(__INTEL_COMPILER)
 # pragma clang diagnostic pop
 #endif
 

ProcessUNIX.c

@@ -1595,12 +1595,12 @@ static void kwsysProcessVolatileFree(volatile void* p)
 {
   /* clang has made it impossible to free memory that points to volatile
      without first using special pragmas to disable a warning...  */
-#if defined(__clang__)
+#if defined(__clang__) && !defined(__INTEL_COMPILER)
 # pragma clang diagnostic push
 # pragma clang diagnostic ignored "-Wcast-qual"
 #endif
   free((void*)p); /* The cast will silence most compilers, but not clang.  */
-#if defined(__clang__)
+#if defined(__clang__) && !defined(__INTEL_COMPILER)
 # pragma clang diagnostic pop
 #endif
 }