build: Provide ntbtls.pc, generated by configure.
* configure.ac (PACKAGE, VERSION): Remove. Generate src/ntbtls.pc. * src/Makefile.am (pkgconfigdir, pkgconfig_DATA): New. (EXTRA_DIST): Add ntbtls.pc.in. * src/ntbtls-config.in: Use @PACKAGE_VERSION@. * src/ntbtls.pc.in: New.
- Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>