Makefile: build fuchsia go binaries using the sdk

This commit removes a dependency on fuchsia's tools/devshell/contrib/go,
which was removed recently[0].

Now to build go binaries for fuchsia we are not relying on the
fuchsia.git repo at all. The code just needs a copy of the fuchsia
//third_party/go repository, the fuchsia sdk and a copy of clang.

Users should download the sdk and clang beforehand (see documentation
for links), and then run (with the correct environment variables):

```
$ make TARGETOS=fuchsia TARGETARCH=amd64 \
    SOURCEDIR=$HOME/fuchsia \
    FX_SDK_PATH=${HOME}/sdk/fuchsia-sdk \
    CLANG_PATH=${HOME}/sdk/clang \
    fuchsia_go
```

After that, they will be able to build the syzkaller go binaries by
doing:

```
$ make TARGETOS=fuchsia TARGETARCH=amd64 \
    SOURCEDIR=$HOME/fuchsia \
    FX_SDK_PATH=${HOME}/sdk/fuchsia-sdk \
    CLANG_PATH=${HOME}/sdk/clang
```

This commits adds two scripts to tools/fuchsia, one for building go in
fuchsia (just calls the ./make.all script in fuchsia's go repo), and one
that replaces the devshell/contrib/go script.

Given that go is unsupported in fuchsia, this change might break at any
point.

[0]: https://fuchsia-review.googlesource.com/c/fuchsia/+/291631

1 files changed, 9 insertions, 2 deletions

diff --git a/Makefile b/Makefile
index 5372a899f..4bf64a8a1 100644
--- a/Makefile
+++ b/Makefile
@@ -45,8 +45,9 @@ TARGETGOOS := $(TARGETOS)
 TARGETGOARCH := $(TARGETVMARCH)
 
 ifeq ("$(TARGETOS)", "fuchsia")
-	# SOURCEDIR should point to fuchsia checkout.
-	GO = "$(SOURCEDIR)/tools/devshell/contrib/go"
+# SOURCEDIR should point to fuchsia checkout.
+export FX_SRC_PATH=$(SOURCEDIR)
+	GO = "tools/fuchsia/go"
 endif
 
 GITREV=$(shell git rev-parse HEAD)
@@ -202,6 +203,12 @@ ifeq ($(TARGETOS),fuchsia)
 else
 endif
 
+fuchsia_go:
+ifeq ($(TARGETOS),fuchsia)
+	./tools/fuchsia/build-go.sh
+else
+endif
+
 generate_trace2syz:
 	(cd tools/syz-trace2syz/parser; ragel -Z -G2 -o lex.go straceLex.rl)
 	(cd tools/syz-trace2syz/parser; goyacc -o strace.go -p Strace -v="" strace.y)