* config/tcl.m4 (SC_PATH_TCLCONFIG): Don't exit 0 if tclconfig fails.

	(SC_PATH_TKCONFIG): Don't exit 0 if tkconfig fails.
	(SC_LOAD_TCLCONFIG): Quote all uses of TCL_BIN_DIR, it may contain
	"# no Tcl configs found".
	(SC_LOAD_TKCONFIG): Similarily for TK_BIN_DIR.

	* gdb/configure.ac (gdbkt): Check both no_tcl/no_tk first, before
	doing any further tcl/tk configury.  Don't configure gdbtk if
	tcl or tk check fails.
	* gdb/aclocal.m4: Regenerate.
	* gdb/configure: Regenerate.
	* gdb/gdbtk/plugins/aclocal.m4: Regenerate.
	* gdb/gdbtk/plugins/configure: Regenerate.