Bug 1553810 - remove RSSRCS support from the build system; r=nalexander

We used to support specifying single Rust files for compilation,
emphasis on "used to".

Differential Revision: https://phabricator.services.mozilla.com/D32314

--HG--
extra : moz-landing-system : lando

config/rules.mk

@@ -714,11 +714,8 @@ $(foreach f,$(HOST_CSRCS) $(HOST_CPPSRCS) $(HOST_CMSRCS) $(HOST_CMMSRCS),$(eval
 
 # The Rust compiler only outputs library objects, and so we need different
 # mangling to generate dependency rules for it.
-mk_libname = $(basename lib$(notdir $1)).rlib
-src_libdep = $(call mk_libname,$1): $1 $$(call mkdir_deps,$$(MDDEPDIR))
 mk_global_crate_libname = $(basename lib$(notdir $1)).$(LIB_SUFFIX)
 crate_src_libdep = $(call mk_global_crate_libname,$1): $1 $$(call mkdir_deps,$$(MDDEPDIR))
-$(foreach f,$(RSSRCS),$(eval $(call src_libdep,$(f))))
 $(foreach f,$(RS_STATICLIB_CRATE_SRC),$(eval $(call crate_src_libdep,$(f))))
 
 $(OBJS) $(HOST_OBJS) $(PROGOBJS) $(HOST_PROGOBJS): $(GLOBAL_DEPS)

python/mozbuild/mozbuild/backend/recursivemake.py

@@ -467,7 +467,6 @@ class RecursiveMakeBackend(CommonBackend):
                 '.m': 'CMSRCS',
                 '.mm': 'CMMSRCS',
                 '.cpp': 'CPPSRCS',
-                '.rs': 'RSSRCS',
                 '.S': 'SSRCS',
             }
             variables = [suffix_map[obj.canonical_suffix]]