[liba] Add a bridge for incomplete libc

For example, GLIBC doesn't provide strlcpy which we want to use

Change-Id: Iebbadfd42ca8e5dc089a8fe0b670fef843a10027

liba/Makefile.bridge

@@ -0,0 +1,3 @@
+SFLAGS += -Iliba/include/bridge
+
+objs += liba/src/bridge.o

liba/include/bridge/string.h

@@ -0,0 +1,16 @@
+#ifndef LIBA_BRIDGE_STRING_H
+#define LIBA_BRIDGE_STRING_H
+
+#include_next <string.h>
+
+#include "../private/macros.h"
+
+LIBA_BEGIN_DECLS
+
+#if __GLIBC__
+size_t strlcpy(char * dst, const char * src, size_t len);
+#endif
+
+LIBA_END_DECLS
+
+#endif

liba/src/bridge.c

@@ -0,0 +1,5 @@
+#include <string.h>
+
+#if __GLIBC__
+#include "strlcpy.c"
+#endif