8308288: Fix xlc17 clang warnings and build errors in hotspot

Reviewed-by: goetz, mbaesken

src/hotspot/share/runtime/os.cpp

@@ -162,7 +162,7 @@ char* os::iso8601_time(jlong milliseconds_since_19700101, char* buffer, size_t b
   // No offset when dealing with UTC
   time_t UTC_to_local = 0;
   if (!utc) {
-#if defined(_ALLBSD_SOURCE) || defined(_GNU_SOURCE)
+#if (defined(_ALLBSD_SOURCE) || defined(_GNU_SOURCE)) && !defined(AIX)
     UTC_to_local = -(time_struct.tm_gmtoff);
 #elif defined(_WINDOWS)
     long zone;
@@ -878,8 +878,8 @@ bool os::print_function_and_library_name(outputStream* st,
   // this as a function descriptor for the reader (see below).
   if (!have_function_name && os::is_readable_pointer(addr)) {
     address addr2 = (address)os::resolve_function_descriptor(addr);
-    if (have_function_name = is_function_descriptor =
-        dll_address_to_function_name(addr2, p, buflen, &offset, demangle)) {
+    if ((have_function_name = is_function_descriptor =
+        dll_address_to_function_name(addr2, p, buflen, &offset, demangle))) {
       addr = addr2;
     }
   }

src/hotspot/share/utilities/globalDefinitions_xlc.hpp

@@ -32,12 +32,22 @@
 // globally used constants & types, class (forward)
 // declarations and a few frequently used utility functions.
 
+#include <alloca.h>
 #include <ctype.h>
 #include <string.h>
 #include <stdarg.h>
 #include <stddef.h>
 #include <stdio.h>
 #include <stdlib.h>
+// In stdlib.h on AIX malloc is defined as a macro causing
+// compiler errors when resolving them in different depths as it
+// happens in the log tags. This avoids the macro.
+#if (defined(__VEC__) || defined(__AIXVEC)) && defined(AIX) \
+    && defined(__open_xl_version__) && __open_xl_version__ >= 17
+  #undef malloc
+  extern void *malloc(size_t) asm("vec_malloc");
+#endif
+
 #include <wchar.h>
 
 #include <math.h>