build: introduce shared libreiserfscore.so and export it

In order to use reiserfs functionality in external programs, we need to
make a shared library and includes available.

This converts both libmisc and libreiserfscore into shared libraries, and
links libmisc into libreiserfscore. We also export the includes and
a pkg-config file.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>

reiserfscore/reiserfscore.pc.in

@@ -0,0 +1,10 @@
+prefix=@prefix@
+exec_prefix=@exec_prefix@
+libdir=@libdir@
+includedir=@includedir@
+
+Name: reiserfscore
+Description: ReiserFS Core Library
+Version: @REISERFSPROGS_VERSION@
+Cflags: -I${includedir}/reiserfs -I${includedir}
+Libs: -L${libdir} -lreiserfscore