Bug 1963727 - Set dlltool when building rust code while targeting mingw. r=firefox-build-system-reviewers,sergesanspaille

The rust compiler needs to use dlltool since the chrono upgrade because
of the use of raw-dylibs, and this requires the tool to be used from the
right location, which we already have out of configure.

Differential Revision: https://phabricator.services.mozilla.com/D247533

config/makefiles/rust.mk

@@ -325,6 +325,10 @@ RUSTC_BOOTSTRAP := 1
 endif
 endif
 
+ifeq (WINNT_clang,$(OS_ARCH)_$(CC_TYPE))
+RUSTFLAGS += -C dlltool=$(LLVM_DLLTOOL)
+endif
+
 $(target_rust_ltoable): RUSTFLAGS:=$(rustflags_override) $(rustflags_sancov) $(RUSTFLAGS) $(rust_pgo_flags) \
 								$(if $(MOZ_LTO_RUST_CROSS),\
 								    -Clinker-plugin-lto \