openblas: fix build on ppc64le/ppc64 glibc

on musl, __builtin_cpu_is will always return 0 because it relies
on glibc funcitonality, on glibc it will fail to compile because
power10 is only an allowed argument from gcc10

srcpkgs/openblas/patches/ppc-dynamic-gcc9.patch

@@ -0,0 +1,25 @@
+From 7a3c188fb1bf669aa4cf571e1e6fbcd1692f4f7a Mon Sep 17 00:00:00 2001
+From: q66 <daniel@octaforge.org>
+Date: Sun, 3 Jan 2021 13:16:16 +0100
+Subject: [PATCH] fix build on gcc9
+
+---
+ driver/others/dynamic_power.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git driver/others/dynamic_power.c driver/others/dynamic_power.c
+index a2f56d8..e79e7e9 100644
+--- driver/others/dynamic_power.c
++++ driver/others/dynamic_power.c
+@@ -53,7 +53,7 @@ static gotoblas_t *get_coretype(void) {
+ 		return &gotoblas_POWER10;
+ #endif
+ 	/* Fall back to the POWER9 implementation if the toolchain is too old or the MMA feature is not set */
+-#if (!defined __GNUC__) || ( __GNUC__ >= 6)
++#if (!defined __GNUC__) || ( __GNUC__ >= 10)
+ 	if (__builtin_cpu_is("power10"))
+ 		return &gotoblas_POWER9;
+ #endif	
+-- 
+2.30.0
+