infer SYSROOT from the cross cpp's idea of pthread.h location Until now, SYSROOT was always assumed to be $(TOOLCHAIN_DIR), but neither backfire nor external toolchains put their core headers into $(TOOLCHAIN_DIR)/include, therfore feature detection failed badly.

libs/re/Makefile

@@ -35,7 +35,7 @@ define Build/Compile
 		EXTRA_CFLAGS="$(TARGET_CFLAGS) -DOPENWRT" \
 		EXTRA_LFLAGS="-lm" \
 		DESTDIR="$(PKG_INSTALL_DIR)" \
-		SYSROOT="$(TOOLCHAIN_DIR)" \
+		SYSROOT="$$$$(echo '#include <pthread.h>' | $(TARGET_CROSS)cpp -x c | sed -ne 's,^# [0-9]* \"\(.*\)/include/pthread\.h\".*,\1,p' | head -n1)" \
 		SYSROOT_ALT="$(STAGING_DIR)/usr" \
 		RELEASE=1 \
 		CROSS_COMPILE="$(TARGET_CROSS)" \

libs/re/patches/200-stdint.h.patch

@@ -1,10 +0,0 @@
---- a/include/re_types.h
-+++ b/include/re_types.h
-@@ -5,6 +5,7 @@
-  */
- 
- #include <sys/types.h>
-+#include <stdint.h>
- 
- #ifdef _MSC_VER
- #include <stdlib.h>