contrib: pthreads: Use the right CONTEXT field on arm64

(cherry picked from commit 6869332cc1)
Signed-off-by: Hugo Beauzée-Luyssen <hugo@beauzee.fr>

contrib/src/pthreads/arm64.patch

@@ -0,0 +1,14 @@
+diff -urN pthreads-orig/context.h pthreads/context.h
+--- pthreads-orig/context.h	2011-03-04 01:37:20.000000000 +0200
++++ pthreads/context.h	2018-03-18 13:50:07.362676429 +0200
+@@ -67,6 +67,10 @@
+ #define PTW32_PROGCTR(Context)  ((Context).Pc)
+ #endif
+ 
++#if defined(_ARM64_) || defined(__aarch64__)
++#define PTW32_PROGCTR(Context)  ((Context).Pc)
++#endif
++
+ #if !defined(PTW32_PROGCTR)
+ #error Module contains CPU-specific code; modify and recompile.
+ #endif

contrib/src/pthreads/rules.mak

@@ -22,6 +22,7 @@ endif
 	$(APPLY) $(SRC)/pthreads/implib.patch
 	$(APPLY) $(SRC)/pthreads/remove-inline.patch
 	$(APPLY) $(SRC)/pthreads/x86-inline-asm.patch
+	$(APPLY) $(SRC)/pthreads/arm64.patch
 	$(MOVE)
 
 ifdef HAVE_CROSS_COMPILE