build: drop support for darwin-386

The new sys package drops support.

Author: Stebalien

mk/util.mk

@@ -18,9 +18,6 @@ SUPPORTED_PLATFORMS += linux-386
 SUPPORTED_PLATFORMS += linux-amd64
 
 SUPPORTED_PLATFORMS += darwin-amd64
-ifeq ($(shell bin/check_go_version "1.15.0" 2>/dev/null; echo $$?),1)
-SUPPORTED_PLATFORMS += darwin-386
-endif
 ifeq ($(shell bin/check_go_version "1.16.0" 2>/dev/null; echo $$?),0)
 SUPPORTED_PLATFORMS += darwin-arm64
 endif