INSTALL.md: add clang for install build dependence

[Bojun-Seo]

clang is not default package of Ubuntu 24.04. So, add clang for install build dependence on INSTALL.md file.

You will get following error during compiling libbpf-tools on Ubuntu 24.04 without this patch.

  MKDIR    .output                                                                          
  BPF      memleak.bpf.o                                                                                                                                                             
/bin/sh: 1: clang: not found
make: *** [Makefile:209: /home/bojun/bcc/libbpf-tools/.output/memleak.bpf.o] Error 127

I guess other Ubuntu versions also need clang for install dependence. But I didn't test it on other versions.

[Bojun-Seo]

I will test this again and change the status to open.

[Bojun-Seo]

I've tested again on freshly installed Ubuntu 24.04 and clang and llvm packages are necessary to build tools in libbpf-tools

[ekyooo]

Thank you. The change is only required for building libbpf-tools, not the BCC Python tools. Adding a note (or a dedicated subsection) to clarify this would improve the documentation.

In the longer term, if the BCC Python tools and libbpf-tools diverge significantly in build requirements, splitting them into separate "Install build dependencies" sections would make the document clearer and more user-friendly. A contribution for that would be very welcome.

[Bojun-Seo]

Thank you. The change is only required for building libbpf-tools, not the BCC Python tools. Adding a note (or a dedicated subsection) to clarify this would improve the documentation.

Thanks for the feedback. I've updated it by adding a dedicated subsection.

In the longer term, if the BCC Python tools and libbpf-tools diverge significantly in build requirements, splitting them into separate "Install build dependencies" sections would make the document clearer and more user-friendly. A contribution for that would be very welcome.

I agree with you.