Don't define abs_* variables ourselves

Apparently this was necessary in the past because old versions
of autoconf/automake didn't make them available, but these
days all of the platforms we target include recent enough
autotools - as evidenced by the fact that, for example, we
already use abs_top_srcdir in tools/ despite the fact that
tools/Makefile.am is missing the same boilerplate.
Signed-off-by: NAndrea Bolognani <abologna@redhat.com>
Reviewed-by: NMartin Kletzander <mkletzan@redhat.com>

src/Makefile.am

@@ -16,12 +16,6 @@
 ## License along with this library.  If not, see
 ## <http://www.gnu.org/licenses/>.
 
-# old automake does not provide abs_{src,build}dir variables
-abs_builddir = $(shell pwd)
-abs_top_builddir = $(shell cd .. && pwd)
-abs_srcdir = $(shell cd $(srcdir) && pwd)
-abs_top_srcdir = $(shell cd $(top_srcdir) && pwd)
-
 # No libraries with the exception of LIBXML should be listed
 # here. List them against the individual XXX_la_CFLAGS targets
 # that actually use them.

tests/Makefile.am

@@ -16,12 +16,6 @@
 ## License along with this library.  If not, see
 ## <http://www.gnu.org/licenses/>.
 
-# old automake does not provide abs_{src,build}dir variables
-abs_builddir = $(shell pwd)
-abs_top_builddir = $(shell cd .. && pwd)
-abs_srcdir = $(shell cd $(srcdir) && pwd)
-abs_top_srcdir = $(shell cd $(top_srcdir) && pwd)
-
 SHELL = $(PREFERABLY_POSIX_SHELL)
 
 AM_CPPFLAGS = \