Merge #90: pkgconfig: Use @CMAKE_INSTALL_LIBDIR@ variable

0f9605b pkgconfig: Use @CMAKE_INSTALL_LIBDIR@ variable (Ryan Ofsky)

Pull request description:

  Use @CMAKE_INSTALL_LIBDIR@ variable instead of hardcoding "lib" as the libdir. This is needed after 54bd57f (#79) which changed the installation to sometimes install to "lib64".

  This fixes error "ld: cannot find -lmultiprocess: No such file or directory" in Bitcoin Core.

  Also replace hardcoded "include" with @CMAKE_INSTALL_INCLUDEDIR@ for consistency.

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Tree-SHA512: f6bf645b9ad9575b4f1847a65839de01546dea574787ac1789cfffc9b144545dfc70b552d986e003ef845c40b011393b6be0d1e324e4bd6ba4e4e89d29c3a91a

Author: ryanofsky

pkgconfig/libmultiprocess.pc.in

@@ -1,7 +1,7 @@
 prefix=@CMAKE_INSTALL_PREFIX@
 exec_prefix=${prefix}
-libdir=${prefix}/lib
-includedir=${prefix}/include
+libdir=${prefix}/@CMAKE_INSTALL_LIBDIR@
+includedir=${prefix}/@CMAKE_INSTALL_INCLUDEDIR@
 capnp_prefix=@capnp_PREFIX@
 
 Name: libmultiprocess