gpg-error-config: Add PKG_CONFIG_SYSROOT_DIR support.
* src/gpg-error-config-new.in (sysroot): New function. (want_cflags, want_libs): Use sysroot. * src/gpg-error-config-test.sh: Test with PKG_CONFIG_SYSROOT_DIR.
PKG_CONFIG_SYSROOT_DIR is for cross build.
- Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>