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>

include/Makefile.am

@@ -1 +1,3 @@
-noinst_HEADERS = io.h  misc.h  reiserfs_fs.h  reiserfs_lib.h swab.h parse_time.h progbar.h
+noinst_HEADERS = parse_time.h progbar.h
+reiserfsdir = $(includedir)/reiserfs
+reiserfs_HEADERS = io.h misc.h reiserfs_fs.h reiserfs_lib.h swab.h