recipetool: create: improve extraction of pkg-config / lib deps
* The regexes for PKG_CHECK_MODULES / AC_CHECK_LIB were a bit too strict
and thus we were skipping some macros.
* Add support for PKG_CHECK_EXISTS
* Avoid duplicates in warning on missing pkg-config dependencies
* Ignore dependency on musl (since this may come up if it's the selected
C library)
Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
