Fix build on iOS

[jeanregisser]

This PR fixes a compilation error on iOS as seen in ethereum/go-ethereum#20160

Unfortunately libproc.h is not included in the iOS SDK. The missing headers were taken from Xcode 11.3.1 (/Applications/Xcode11.3.1.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/).

Let me know what you think. Thanks.

[cla-checker-service]

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[holiman]

ping @jeanregisser would you be open to signing that CLA? I guess this PR is blocked for that reason

[jeanregisser]

Yes I did follow the process and signed the document on DocuSign but somehow the bot didn’t update the status.

I’ll retry today.

[arnaubennassar]

Is there any update on this?

[andrewkroh]

We don't want to include and maintain Apple's headers in this project. Apple should add the necessary headers to their IOS SDK if they are meant to be used to IOS projects. I recommend using tags to exclude the use of gosigar from projects that need to compile for mobile.

I think we would accept a patch to include sigar_stub.go for IOS. It would need to be accompanied by tests on Travis CI that verify builds work for gomobile build -target=ios -x ., GOOS=darwin GOARCH=amd64 build, and GOOS=darwin GOARCH=386 go build ..

I did check if the MacOS SDK would work unmodified, but, no, it did not work without cherry-picking particular files as this PR has done. Specifically some of the headers complain that architecture not supported due to ARM.

The other issue I encountered is that gomobile doesn't support -gccgoflags or CGO_CFLAGS. So you cannot pass through the CFLAGS option. The only way I could set the value was by adding a source file with a CGO "comment" that set CFLAGS. From gomobile help build:

The build flags -a, -i, -n, -x, -gcflags, -ldflags, -tags, -trimpath, and -work are
shared with the build command. For documentation, see 'go help build'.

[user1121114685]

感谢你的支持，成功的解决了编译错误的问题,这个修复在
https://github.com/shirou/gopsutil
中支持良好，一次性解决了编译问题，非常感谢。