depends: enable lto support for Apple's ld64

Note that this does not _enable_ lto by default in any way, only hooks up the
machinery for -flto to work correctly.

enable-lto-support is explicitly used for pinned-clang because we know it
works. It is neither enabled nor disabled in the external clang case so that
it can be auto-detected.

Author: theuni

depends/packages/native_cctools.mk

@@ -63,9 +63,10 @@ endef
 endif
 
 define $(package)_set_vars
-  $(package)_config_opts=--target=$(host) --disable-lto-support --with-libtapi=$($(package)_extract_dir)
+  $(package)_config_opts=--target=$(host) --with-libtapi=$($(package)_extract_dir)
   $(package)_ldflags+=-Wl,-rpath=\\$$$$$$$$\$$$$$$$$ORIGIN/../lib
   ifeq ($(strip $(FORCE_USE_SYSTEM_CLANG)),)
+  $(package)_config_opts+=--enable-lto-support --with-llvm-config=$($(package)_extract_dir)/toolchain/bin/llvm-config
   $(package)_cc=$($(package)_extract_dir)/toolchain/bin/clang
   $(package)_cxx=$($(package)_extract_dir)/toolchain/bin/clang++
   else