Add -Dcc_as_ld to configure

In MacOSX it may not be possible to build 32-bit perl executable
because "Configure" decides to use "ld" as linker instead of "cc"
for non-ELF host.  Compilation fails because ld by default to
64-bit but the prebuilts/gcc/darwin-x86/host/i686-apple-darwin-4.2.1
defaults to 32-bit.

Change-Id: Id12d46243cd18310e3910c5f62b05fe3a90fbc01