[PATCH] fix build on uClibc without UCLIBC_HAS_BACKTRACE

Backtrace support is only used for logging on signal errors, which
isn't really critical, so simply remove backtrace info if not
available in uClibc.

NOTE: based on patch from Peter Korsgaard <jacmet@sunsite.dk>

Signed-off-by: Petr Vorel <petr.vorel@gmail.com>
---
--- ofono-1.7.orig/src/log.c
+++ ofono-1.7/src/log.c
@@ -30,7 +30,8 @@
 #include <stdlib.h>
 #include <string.h>
 #include <syslog.h>
-#ifdef __GLIBC__
+#if defined(__GLIBC__) && !(defined(__UCLIBC__) && !defined (__UCLIBC_HAS_BACKTRACE__))
+#define HAVE_BACKTRACE
 #include <execinfo.h>
 #endif
 #include <dlfcn.h>
@@ -115,7 +116,7 @@
	va_end(ap);
 }
 
-#ifdef __GLIBC__
+#ifdef HAVE_BACKTRACE
 static void print_backtrace(unsigned int offset)
 {
 	void *frames[99];
@@ -309,7 +310,7 @@
	if (detach == FALSE)
		option |= LOG_PERROR;
 
-#ifdef __GLIBC__
+#ifdef HAVE_BACKTRACE
	signal_setup(signal_handler);
 #endif

@@ -326,7 +327,7 @@

	closelog();

-#ifdef __GLIBC__
+#ifdef HAVE_BACKTRACE
	signal_setup(SIG_DFL);
 #endif