add patch to disable arm vdso in musl 1.2.0

reportedly the vdso version of clock_gettime64 produces erratic
results on arm with linux 5.6, and earlier versions did not have the
vdso function at all. it's not clear what the eventual upstream
solution will be, but something needs to be done so as not to be
producing binaries that seem to work now but will break fantastically
when moving to newer kernels.

patches/musl-1.2.0/0001-broken_arm_vdso.diff

@@ -0,0 +1,17 @@
+diff --git a/arch/arm/syscall_arch.h b/arch/arm/syscall_arch.h
+index 4b08762d..a877b2cf 100644
+--- a/arch/arm/syscall_arch.h
++++ b/arch/arm/syscall_arch.h
+@@ -98,12 +98,6 @@ static inline long __syscall6(long n, long a, long b, long c, long d, long e, lo
+ 	__asm_syscall(R7_OPERAND, "0"(r0), "r"(r1), "r"(r2), "r"(r3), "r"(r4), "r"(r5));
+ }
+ 
+-#define VDSO_USEFUL
+-#define VDSO_CGT32_SYM "__vdso_clock_gettime"
+-#define VDSO_CGT32_VER "LINUX_2.6"
+-#define VDSO_CGT_SYM "__vdso_clock_gettime64"
+-#define VDSO_CGT_VER "LINUX_2.6"
+-
+ #define SYSCALL_FADVISE_6_ARG
+ 
+ #define SYSCALL_IPC_BROKEN_MODE