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>

resize_reiserfs/Makefile.am

@@ -4,5 +4,5 @@ resize_reiserfs_SOURCES = fe.c resize_reiserfs.c do_shrink.c resize.h
 man_MANS = resize_reiserfs.8
 EXTRA_DIST = $(man_MANS)
 
-LDADD = $(top_builddir)/reiserfscore/libcore.a $(top_builddir)/lib/libmisc.a
+LDADD = $(top_builddir)/reiserfscore/libreiserfscore.la