Makefile.def: drop remnants of unused libelf

Use of libelf was removed from gcc in r0-104274-g48215350c24d52 ("re PR
lto/46273 (Failed to bootstrap)") around 2010, before gcc-4.6.0.

This change removes unused references to libelf from top-level configure
and Makefile.

	* Makefile.def: Drop libelf module and gcc-configure dependency
	on it.
	* Makefile.tpl (HOST_EXPORTS): Drop unused LIBELFLIBS and
	LIBELFINC.

Makefile.def

@@ -71,9 +71,6 @@ host_modules= { module= isl; lib_path=.libs; bootstrap=true;
 		extra_configure_flags='--disable-shared @extra_isl_gmp_configure_flags@  @host_libs_picflag@';
 		extra_make_flags='V=1';
 		no_install= true; };
-host_modules= { module= libelf; lib_path=.libs; bootstrap=true;
-		extra_configure_flags='--disable-shared';
-		no_install= true; };
 host_modules= { module= gold; bootstrap=true; };
 host_modules= { module= gprof; };
 host_modules= { module= gprofng; };
@@ -358,7 +355,6 @@ dependencies = { module=configure-gcc; on=all-binutils; };
 dependencies = { module=configure-gcc; on=all-gas; };
 dependencies = { module=configure-gcc; on=all-ld; };
 dependencies = { module=configure-gcc; on=all-gold; };
-dependencies = { module=configure-gcc; on=all-libelf; };
 dependencies = { module=configure-gcc; on=all-libiconv; };
 dependencies = { module=all-gcc; on=all-libiberty; hard=true; };
 dependencies = { module=all-gcc; on=all-intl; };

Makefile.tpl

@@ -243,8 +243,6 @@ HOST_EXPORTS = \
 	GMPINC="$(HOST_GMPINC)"; export GMPINC; \
 	ISLLIBS="$(HOST_ISLLIBS)"; export ISLLIBS; \
 	ISLINC="$(HOST_ISLINC)"; export ISLINC; \
-	LIBELFLIBS="$(HOST_LIBELFLIBS)"; export LIBELFLIBS; \
-	LIBELFINC="$(HOST_LIBELFINC)"; export LIBELFINC; \
 	XGCC_FLAGS_FOR_TARGET="$(XGCC_FLAGS_FOR_TARGET)"; export XGCC_FLAGS_FOR_TARGET; \
 @if gcc-bootstrap
 	$(RPATH_ENVVAR)=`echo "$(TARGET_LIB_PATH)$$$(RPATH_ENVVAR)" | sed 's,::*,:,g;s,^:*,,;s,:*$$,,'`; export $(RPATH_ENVVAR); \
@@ -348,10 +346,6 @@ HOST_GMPINC = @gmpinc@
 HOST_ISLLIBS = @isllibs@
 HOST_ISLINC = @islinc@
 
-# Where to find libelf
-HOST_LIBELFLIBS = @libelflibs@
-HOST_LIBELFINC = @libelfinc@
-
 # ----------------------------------------------
 # Programs producing files for the BUILD machine
 # ----------------------------------------------