Drop subset tarball and replace it with "configure --enable-subset"

There's no point creating two separate tarfiles.  It's not clear
anyone was actually using the subset tarball --- and if they are, they
can replace it by the full source distribution and using the
--enable-subset option.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
diff --git a/configure.ac b/configure.ac
index 81173d0..f365cfa 100644
--- a/configure.ac
+++ b/configure.ac
@@ -565,6 +565,21 @@
 AC_SUBST(DEPPROFILED_LIBBLKID)
 AC_SUBST(BLKID_CMT)
 dnl
+dnl handle --enable-subset
+dnl
+ALL_CMT=
+AC_ARG_ENABLE([subset],
+[  --enable-subset  	  enable subset-only build],
+if test "$enableval" = "no"
+then
+	AC_MSG_RESULT([Disabling subset-only build])
+else
+	ALL_CMT=#
+	AC_MSG_RESULT([Enabling subset-only-build])
+fi
+,)
+AC_SUBST(ALL_CMT)
+dnl
 dnl handle --disable-backtrace
 dnl
 AH_TEMPLATE([DISABLE_BACKTRACE], [Define to 1 to disable use of backtrace])