depends: remove (darwin) libtool now that it's no longer used

Note that this is completely unrelated to gnu usage of libtool.

depends/hosts/default.mk

@@ -7,7 +7,6 @@ default_host_CXX = $(host_toolchain)g++
 default_host_AR = $(host_toolchain)ar
 default_host_RANLIB = $(host_toolchain)ranlib
 default_host_STRIP = $(host_toolchain)strip
-default_host_LIBTOOL = $(host_toolchain)libtool
 default_host_NM = $(host_toolchain)nm
 default_host_OBJCOPY = $(host_toolchain)objcopy
 
@@ -39,5 +38,5 @@ host_$1 = $$($(host_arch)_$(host_os)_$1)
 host_$(release_type)_$1 = $$($(host_arch)_$(host_os)_$(release_type)_$1)
 endef
 
-$(foreach tool,CC CXX AR RANLIB STRIP LIBTOOL NM OBJCOPY OTOOL INSTALL_NAME_TOOL DSYMUTIL,$(eval $(call add_host_tool_func,$(tool))))
+$(foreach tool,CC CXX AR RANLIB STRIP NM OBJCOPY OTOOL INSTALL_NAME_TOOL DSYMUTIL,$(eval $(call add_host_tool_func,$(tool))))
 $(foreach flags,CFLAGS CXXFLAGS CPPFLAGS LDFLAGS, $(eval $(call add_host_flags_func,$(flags))))