Static builds: Make sure they work, add CI tests about bpftool HOT 1 CLOSED

Libbfd

In the Linux repo: Passing the --static flag via $(CFLAGS) does not work, because the flag is not passed down to the feature detection system. Therefore, the library flags ($(LIBS)) may lack -liberty and -lz. Using EXTRA_CFLAGS=--static instead works fine.

In the mirror: We do pass the $(CFLAGS) (containing the $(EXTRA_CFLAGS) to the feature detection system, which we may want to change, by the way. But we're only compiling to assembly, not linking, so we're not able to detect the correct set of libraries. This needs to be fixed.

LLVM

$ git clone https://github.com/llvm/llvm-project.git
$ mkdir llvm-project/llvm/build
$ cd llvm-project/llvm/build
$ cmake .. -DCMAKE_BUILD_TYPE=Release
$ make -j llvm-config llvm-libraries

$ cd /path/to/bpftool
$ LLVM_CONFIG=path/to/llvm-project/llvm/build/bin/llvm-config EXTRA_CFLAGS=--static make -j

It's possible that a subset of the libraries would be enough to get the disassembler. It would be great, because compiling all libraries takes time.

from bpftool.