libgrypt.pc: Provide pkg-config file.
* configure.ac: Generate src/libgcrypt.pc. * src/Makefile.am (pkgconfigdir, pkgconfig_DATA): New. (EXTRA_DIST): Add libgcrypt.pc.in. * src/libgcrypt.pc.in: New.
Backported from master.
- Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>