Deduplicate options to compiler and linker, as well as consecutive LIBS

Deduplicate options to compiler and linker, as well as consecutive LIBS

	* configure.ac: Use SXE_{APPEND,PREPEND}_UNDUP do add to c_switch_site and ld_switch_site
	* configure.ac: Ditto for adding to c_switch_gtk
	* configure.ac: Ditto for adding to X_CFLAGS
	* configure.ac: Ditto for adding to MM_CFLAGS, MM_LDFLAGS and MM_CPPFLAGS

	* configure.ac: Use SXE_CONSECUTIVE_UNDUP instead of SXE_SPACE to remove consecutive dups on libs_xauth
	* configure.ac: Ditto for ld_libs_general, ld_libs_window_system and ld_libs_all

	* configure.ac: Use SXE_UNDUP to remove dups from {c,ld}_switch_{general,window_system,all}

	* configure.ac: Remove extra verbose output of the switches, since this was moved to sxe-summary.m4

	* m4/sxe-summary.m4 (SXE_SUMMARY): Provide output of {c,ld}_switch_{general,window_system,all}
	* m4/sxe-summary.m4 (SXE_SUMMARY): Don't use -e on echo, since not all shells honor it

	* m4/sxe-bldenv.m4: Use SXE_{APPEND,PREPEND}_UNDUP do add to LD_FLAGS, CPPFLAGS, ld_switch_{run,system,site}
	* m4/sxe-compiler.m4: Use SXE_{APPEND,PREPEND}_UNDUP do add to c_switch_{site,system}, CFLAGS
	* m4/sxe-crypto.m4: Use SXE_{APPEND,PREPEND}_UNDUP do add to CPPFLAGS, LDFLAGS
	* m4/sxe-libtool.m4: Use SXE_{APPEND,PREPEND}_UNDUP do add to LDFLAGS
	* m4/sxe-mm.m4: Use SXE_{APPEND,PREPEND}_UNDUP do add to {c,ld}_switch_site

Signed-off-by: Nelson Ferreira <nelson.ferreira@ieee.org>