Use linker -Wl,--wrap=symbol

Linker --wrap option resolves to __wrap_symbol for undefined symbol.
During the compilation of host libportable.a, __HOST__ is defined
to rename all portable functions to  __wrap_symbol, and the
real function to __real_symbol.  This way libportable.a can be
validated at host w/o changes of user's source code.

See http://sourceware.org/binutils/docs/ld/Options.html

Change-Id: Idcbe53dd642536f3dc2be85a875f95535b9dc0b1

ndk/sources/android/libportable/arch-x86/socket.c

@@ -14,10 +14,11 @@
  * limitations under the License.
  */
 
+#include <portability.h>
 #include <unistd.h>
 #include <sys/socket.h>
 #include <sys/linux-syscalls.h>
 
-int socket_portable(int domain, int type, int protocol) {
-    return socket(domain, type, protocol);
+int WRAP(socket)(int domain, int type, int protocol) {
+    return REAL(socket)(domain, type, protocol);
 }