Remove glibc specific function dependencies

Sourced from: https://git.alpinelinux.org/aports/tree/main/mariadb/ppc-remove-glibc-dep.patch
Signed-off-by: Khem Raj <raj.khem@gmail.com>

diff --git a/include/my_cpu.h b/include/my_cpu.h
index f2e26fca..94599b74 100644
--- a/include/my_cpu.h
+++ b/include/my_cpu.h
@@ -24,17 +24,16 @@
 */

 #ifdef _ARCH_PWR8
-#include <sys/platform/ppc.h>
 /* Very low priority */
-#define HMT_very_low() __ppc_set_ppr_very_low()
+#define HMT_very_low() asm volatile("or 31,31,31")
 /* Low priority */
-#define HMT_low() __ppc_set_ppr_low()
+#define HMT_low() asm volatile ("or 1,1,1")
 /* Medium low priority */
-#define HMT_medium_low() __ppc_set_ppr_med_low()
+#define HMT_medium_low() asm volatile ("or 6,6,6")
 /* Medium priority */
-#define HMT_medium() __ppc_set_ppr_med()
+#define HMT_medium() asm volatile ("or 2,2,2")
 /* Medium high priority */
-#define HMT_medium_high() __ppc_set_ppr_med_high()
+#define HMT_medium_high() asm volatile("or 5,5,5")
 /* High priority */
 #define HMT_high() asm volatile("or 3,3,3")
 #else
@@ -72,7 +71,7 @@ static inline void MY_RELAX_CPU(void)
   __asm__ __volatile__ ("pause");
 #endif
 #elif defined(_ARCH_PWR8)
-  __ppc_get_timebase();
+  __builtin_ppc_get_timebase();
 #elif defined __GNUC__ && (defined __arm__ || defined __aarch64__)
   /* Mainly, prevent the compiler from optimizing away delay loops */
   __asm__ __volatile__ ("":::"memory");