fix build error on ARM due to wrong glibc check

From ae02bfc600bf8c4c8502e70bdf8dfcd332ebef02 Mon Sep 17 00:00:00 2001
From: John Spencer <[email protected]>
Date: Mon, 10 Dec 2012 06:54:03 +0100
Subject: [PATCH 2/4] fix build error on ARM due to wrong glibc check

the test for glibc < 2 "succeeds" wrongly for any non-glibc C library, and breaks the build on musl libc.
we must first test if __GLIBC__ is defined at all, before using it unconditionally.

---
 user-exec.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

index ef9b172..cccc145 100644
@@ -442,7 +442,7 @@ int cpu_signal_handler(int host_signum, void *pinfo,
     unsigned long pc;
     int is_write;
 
-#if (__GLIBC__ < 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ <= 3))
+#if defined(__GLIBC__) && (__GLIBC__ < 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ <= 3))
     pc = uc->uc_mcontext.gregs[R15];
 #else
     pc = uc->uc_mcontext.arm_pc;

1.7.3.4