configure: support --enable-pic for generic-gnu

Allows the default generic-gnu target, which is selected if no
target is specified, to be build in PIC mode. The generic-gnu target
was not being selected as a gcc target, because it doesn't end in
gcc.

Change-Id: I28a2a420109c34fd87a20911f6455c8d8d5ded75

build/make/configure.sh

@@ -780,6 +780,7 @@ process_common_toolchain() {
     ;;
     universal*|*-gcc|generic-gnu)
         link_with_cc=gcc
+        enable gcc
     setup_gnu_toolchain
     ;;
     esac