autotools.bbclass: Add new pattern to match -L<libdir> in dependency_libs

autotools.bbclass: Add new pattern to match -L<libdir> in dependency_libs

	* Current pattern match does one think wrong consider
	something like this
	dependency_libs=' -L/home/kraj/work/oe/build/eglibc/omap5912osk/work/x86_64-linux/ncurses-native-5.4-r17/ncurses-5.4/lib'
	this pattern when matched gets converted to
	dependency_libs=' -L/home/kraj/work/oe/build/eglibc/omap5912osk/staging/x86_64-linux/usr/lib/lib'
	which is wrong. If we had a '/' appended to original path then it would work.
	This patch lets it straight.