docker-distribution: fix for GO cross compilation

With oe-core commit c23f9e80492e4b [tcmode-default: use
go-binary-native by default], we must explictly call the proper
cross go binary, versus just the go-native variant.

These builds were working by luck, since the go compiler was capable
of building the target binaries previously (in its build-from-source
creation). We fixup the calls and we no longer see fpu build issues:

 fatal error: gnu/stubs-soft.h: No such file or directory

    7 | # include <gnu/stubs-soft.h>
      |           ^~~~~~~~~~~~~~~~~~

Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>

recipes-containers/docker-distribution/docker-distribution_git.bb

@@ -6,6 +6,7 @@ LIC_FILES_CHKSUM = "file://LICENSE;md5=d2794c0df5b907fdace235a619d80314"
 SRCREV_distribution="2461543d988979529609e8cb6fca9ca190dc48da"
 SRC_URI = "git://github.com/docker/distribution.git;branch=release/2.7;name=distribution;destsuffix=git/src/github.com/docker/distribution \
            file://docker-registry.service \
+           file://0001-build-use-to-use-cross-go-compiler.patch \
           "
 
 PACKAGES =+ "docker-registry"

recipes-containers/docker-distribution/files/0001-build-use-to-use-cross-go-compiler.patch

@@ -0,0 +1,29 @@
+From 9c27a12dc0bc62b95d7ecf003e7d241b36c3f2e6 Mon Sep 17 00:00:00 2001
+From: Bruce Ashfield <bruce.ashfield@gmail.com>
+Date: Tue, 30 Jun 2020 23:35:05 -0400
+Subject: [PATCH] build: use  to use cross go compiler
+
+We shouldn't be invoking 'go' as the compiler, but instead use
+${GO} which tracks our cross build go compiler for the architecture.
+
+Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>
+---
+ Makefile | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/Makefile b/Makefile
+index 4635c6ec..a95e860e 100644
+--- a/Makefile
++++ b/Makefile
+@@ -88,7 +88,7 @@ FORCE:
+ # Build a binary from a cmd.
+ bin/%: cmd/% FORCE
+ 	@echo "$(WHALE) $@${BINARY_SUFFIX}"
+-	@go build ${GO_GCFLAGS} ${GO_BUILD_FLAGS} -o $@${BINARY_SUFFIX} ${GO_LDFLAGS} ${GO_TAGS}  ./$<
++	@${GO} build ${GO_GCFLAGS} ${GO_BUILD_FLAGS} -o $@${BINARY_SUFFIX} ${GO_LDFLAGS} ${GO_TAGS}  ./$<
+ 
+ binaries: $(BINARIES) ## build binaries
+ 	@echo "$(WHALE) $@"
+-- 
+2.19.1
+