mk: Build crates with relative paths to rustc

configure

@@ -521,6 +521,7 @@ fi
 DEFAULT_BUILD="${CFG_CPUTYPE}-${CFG_OSTYPE}"
 
 CFG_SRC_DIR="$(abs_path $(dirname $0))/"
+CFG_SRC_DIR_RELATIVE="$(dirname $0)/"
 CFG_BUILD_DIR="$(pwd)/"
 CFG_SELF="$0"
 CFG_CONFIGURE_ARGS="$@"
@@ -1558,6 +1559,7 @@ done
 step_msg "writing configuration"
 
 putvar CFG_SRC_DIR
+putvar CFG_SRC_DIR_RELATIVE
 putvar CFG_BUILD_DIR
 putvar CFG_OSTYPE
 putvar CFG_CPUTYPE

mk/crates.mk

@@ -134,7 +134,7 @@ DOC_CRATES := std alloc collections core libc rustc_unicode
 #
 # $(1) is the crate to generate variables for
 define RUST_CRATE
-CRATEFILE_$(1) := $$(S)src/lib$(1)/lib.rs
+CRATEFILE_$(1) := $$(SREL)src/lib$(1)/lib.rs
 RSINPUTS_$(1) := $$(call rwildcard,$(S)src/lib$(1)/,*.rs)
 RUST_DEPS_$(1) := $$(filter-out native:%,$$(DEPS_$(1)))
 NATIVE_DEPS_$(1) := $$(patsubst native:%,%,$$(filter native:%,$$(DEPS_$(1))))

mk/main.mk

@@ -322,6 +322,7 @@ $(foreach host,$(CFG_HOST), \
 # exported
 
 export CFG_SRC_DIR
+export CFG_SRC_DIR_RELATIVE
 export CFG_BUILD_DIR
 ifdef CFG_VER_DATE
 export CFG_VER_DATE

mk/reconfig.mk

@@ -34,4 +34,4 @@ Makefile config.mk: config.stamp
 
 config.stamp: $(S)configure $(S)Makefile.in $(S)src/snapshots.txt
 	@$(call E, cfg: reconfiguring)
-	$(S)configure $(CFG_CONFIGURE_ARGS)
+	$(SREL)configure $(CFG_CONFIGURE_ARGS)

mk/util.mk

@@ -20,3 +20,4 @@ print-%:
 	@echo $*=$($*)
 
 S := $(CFG_SRC_DIR)
+SREL := $(CFG_SRC_DIR_RELATIVE)