flex: create separate package for libfl

Target binaries linked with libfl currently generate a runtime
dependency on the entire flex package (and therefore m4 and bison
too). Copy Debian's approach and create a separate package for libfl.

(From OE-Core rev: 1bc6ad19d56498847dc95cce0ea371ba77eff143)

Signed-off-by: Andre McCurdy <armccurdy@gmail.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-devtools/flex/flex_2.6.0.bb

@@ -43,6 +43,10 @@ do_install_append_class-nativesdk() {
 	create_wrapper ${D}/${bindir}/flex M4=${M4}
 }
 
+PACKAGES =+ "${PN}-libfl"
+
+FILES_${PN}-libfl = "${libdir}/libfl.so.* ${libdir}/libfl_pic.so.*"
+
 RDEPENDS_${PN} += "m4"
 RDEPENDS_${PN}-ptest += "bash gawk"