libtool: Update to 2.4.6 and patch for Cygwin

Signed-off-by: Ray Donnelly <mingw.android@gmail.com>

patches/libtool/2.4.6/2.4.5-pass-ldflags.patch

@@ -0,0 +1,12 @@
+--- libtool-2.4.5.orig/build-aux/ltmain.in	2015-01-16 12:52:04.000000000 -0600
++++ libtool-2.4.5/build-aux/ltmain.in	2015-02-07 22:45:14.421079200 -0600
+@@ -5356,7 +5356,8 @@ func_mode_link ()
+       # -stdlib=*            select c++ std lib with clang
+       -64|-mips[0-9]|-r[0-9][0-9]*|-xarch=*|-xtarget=*|+DA*|+DD*|-q*|-m*| \
+       -t[45]*|-txscale*|-p|-pg|--coverage|-fprofile-*|-F*|@*|-tp=*|--sysroot=*| \
+-      -O*|-g*|-flto*|-fwhopr*|-fuse-linker-plugin|-fstack-protector*|-stdlib=*)
++      -O*|-g*|-flto*|-fwhopr*|-fuse-linker-plugin|-fstack-protector*|-stdlib=*| \
++      -shared-libgcc|-static-libgcc|-static-libgfortran|-static-libstdc++)
+         func_quote_for_eval "$arg"
+ 	arg=$func_quote_for_eval_result
+         func_append compile_command " $arg"

scripts/build/companion_tools/400-libtool.sh

@@ -1,6 +1,6 @@
 # Build script for libtool
 
-CT_LIBTOOL_VERSION=2.2.6b
+CT_LIBTOOL_VERSION=2.4.6
 
 do_companion_tools_libtool_get() {
     CT_GetFile "libtool-${CT_LIBTOOL_VERSION}"     \