Add some basic files

lib/pkgconfig/spm.pc.in

+prefix=@CMAKE_INSTALL_PREFIX@
+exec_prefix=${prefix}
+libdir=${exec_prefix}/lib
+includedir=${exec_prefix}/include
+
+Name: HQR
+Description: Build and Visualize Trees for Hierachical QR Factorizations
+Version: @HQR_VERSION_MAJOR@.@HQR_VERSION_MINOR@.@HQR_VERSION_MICRO@
+Cflags: -I${includedir}
+Libs: -L${libdir} @HQR_PKGCONFIG_LIBS@
+Libs.private: @HQR_PKGCONFIG_LIBS_PRIVATE@
+Requires: @HQR_PKGCONFIG_REQUIRED@
+Requires.private: @HQR_PKGCONFIG_REQUIRED_PRIVATE@