gawk: install /usr/bin/awk as a relative symlink

Fixes:
  http://autobuild.buildroot.net/results/bf3937882023df7ed319dc76f1af10f79785112f/

Signed-off-by: Carlos Santos <casantos@datacom.com.br>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
(cherry picked from commit d4b5a92c53f08b3afad4255b663ac292605d5aa8)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/gawk/gawk.mk

@@ -39,7 +39,7 @@ endif
 HOST_GAWK_CONF_OPTS = --without-readline --without-mpfr
 
 define GAWK_CREATE_SYMLINK
-	ln -sf /usr/bin/gawk $(TARGET_DIR)/usr/bin/awk
+	ln -sf gawk $(TARGET_DIR)/usr/bin/awk
 endef
 
 GAWK_POST_INSTALL_TARGET_HOOKS += GAWK_CREATE_SYMLINK