bcc fail to run on armhf

## My configuration

- Linux kernel version: 5.10
- Compilied bcc version: 0.25.0
- LLVM version: 11.0-51+nmu5

## Problem

I tried to execute my bpf program with bcc on armhf, and I had getting many errors about SMP and registers. Like in #1202 issue, first error was "error: register 'sp' unsuitable for global register variables on this target". Full log in attached file.

[log.txt](https://github.com/iovisor/bcc/files/10765769/log.txt)

## Inspection in bcc

Looks like that the following files doesn't contain information about working with the armhf architecture:
- [arch_helper.h](https://github.com/iovisor/bcc/tree/master/src/cc/frontends/clang/arch_helper.h)
- [b_frontend_action.cc](https://github.com/iovisor/bcc/blob/master/src/cc/frontends/clang/b_frontend_action.cc)
- [bcc_proc.c](https://github.com/iovisor/bcc/blob/master/src/cc/bcc_proc.c)