try again to fix libmisc sharing problem

Issue #297 reported seeing

*** Warning: Linking the shared library libsubid.la against the
*** static library ../libmisc/libmisc.a is not portable!

which commit b5fb1b38ee was supposed
to fix.  But a few commits later it's back.  So try to fix it
in the way the bug reporter suggested.  This broke builds some
other ways, namely a few missing library specifications, so add
those.

Signed-off-by: Serge Hallyn <serge@hallyn.com>

libmisc/Makefile.am

@@ -3,9 +3,9 @@ EXTRA_DIST = .indent.pro xgetXXbyYY.c
 
 AM_CPPFLAGS = -I$(top_srcdir)/lib $(ECONF_CPPFLAGS)
 
-noinst_LIBRARIES = libmisc.a
+noinst_LTLIBRARIES = libmisc.la
 
-libmisc_a_SOURCES = \
+libmisc_la_SOURCES = \
 	addgrps.c \
 	age.c \
 	audit_help.c \
@@ -74,6 +74,6 @@ libmisc_a_SOURCES = \
 	yesno.c
 
 if WITH_BTRFS
-libmisc_a_SOURCES += btrfs.c
+libmisc_la_SOURCES += btrfs.c
 endif