Support cross-compiling for uClibc targets

Disable backtrace support in src/config.h if uClibc is detected.

Tested on the following platforms:

- sh4-linux-uclibc (GCC 4.1.1, uClibc 0.9.29)
- mipsel-linux-uclibc (GCC 4.4.5, uClibc 0.9.29)

To cross-compile:

    $ make CC=mipsel-linux-gcc MALLOC=libc

Signed-off-by: Michael Steinert <mike.steinert@gmail.com>

Closes #537

src/Makefile

@@ -149,7 +149,7 @@ persist-settings: distclean
 	echo REDIS_LDFLAGS=$(REDIS_LDFLAGS) >> .make-settings
 	echo PREV_FINAL_CFLAGS=$(FINAL_CFLAGS) >> .make-settings
 	echo PREV_FINAL_LDFLAGS=$(FINAL_LDFLAGS) >> .make-settings
-	-(cd ../deps && $(MAKE) $(DEPENDENCY_TARGETS))
+	-(cd ../deps && $(MAKE) CC=$(CC) $(DEPENDENCY_TARGETS))
 
 .PHONY: persist-settings
 

src/config.h

@@ -30,6 +30,10 @@
 #ifndef __CONFIG_H
 #define __CONFIG_H
 
+#ifdef __unix
+#include <features.h>
+#endif
+
 #ifdef __APPLE__
 #include <AvailabilityMacros.h>
 #endif
@@ -56,7 +60,7 @@
 #endif
 
 /* Test for backtrace() */
-#if defined(__APPLE__) || defined(__linux__)
+#if (defined(__APPLE__) || defined(__linux__)) && !defined(__UCLIBC__)
 #define HAVE_BACKTRACE 1
 #endif