build: Simplify phony target declaration with wildcards

Also add etags to list of phony targets.
build: Replace cltostr.pl by a shell script

This avoids a dependency on Perl to build OpenCL support.
configure: Add -Wno-maybe-uninitialized to CFLAGS

The warnings generated by -Wmaybe-uninitialized are mostly spurious.
MSVS 2013 Update 2 support

The first MSVS compiler C99 compliant enough to build x264.
Use `CC=cl ./configure` to compile with it.