auto merge of #5576 : yichoi/rust/pull-0327, r=brson

minor fix
configure: cleanup - parsing supported target triples

Author: bors

configure

@@ -572,7 +572,7 @@ fi
 CFG_PREFIX=${CFG_PREFIX%/}
 CFG_HOST_TRIPLES="$(echo $CFG_HOST_TRIPLES | tr ',' ' ')"
 CFG_TARGET_TRIPLES="$(echo $CFG_TARGET_TRIPLES | tr ',' ' ')"
-CFG_SUPPORTED_TARGET_TRIPLES="$(grep ^CC_*=* $CFG_SRC_DIR/mk/platform.mk | sed 's,^[^_]*_,,' | sed 's/\([^=]*\).*/\1/' | xargs)"
+CFG_SUPPORTED_TARGET_TRIPLES="$(grep ^CC_*=* $CFG_SRC_DIR/mk/platform.mk | sed -e 's/^CC_//' -e 's/\([^=]*\).*/\1/' | xargs)"
 
 # copy host-triples to target-triples so that hosts are a subset of targets
 V_TEMP=""