llama.cpp: build fails on 10.15, due to use of 'errno' in src/llama-mmap.cpp; fix contributed to upstream

[mascguy (Christopher Nielsen)]

On macOS 10.15 - and perhaps other systems/OSs - builds fail due to use of errno:

/opt/local/var/macports/build/_opt_macports_sources_ports_latest_llm_llama.cpp/llama.cpp/work/llama.cpp-4508/src/llama-mmap.cpp:159:86: error: use of undeclared identifier 'errno'
            throw std::runtime_error(format("failed to open %s: %s", fname, strerror(errno)));
                                                                                     ^
/opt/local/var/macports/build/_opt_macports_sources_ports_latest_llm_llama.cpp/llama.cpp/work/llama.cpp-4508/src/llama-mmap.cpp:174:73: error: use of undeclared identifier 'errno'
            throw std::runtime_error(format("ftell error: %s", strerror(errno)));
                                                                        ^
/opt/local/var/macports/build/_opt_macports_sources_ports_latest_llm_llama.cpp/llama.cpp/work/llama.cpp-4508/src/llama-mmap.cpp:188:72: error: use of undeclared identifier 'errno'
            throw std::runtime_error(format("seek error: %s", strerror(errno)));
                                                                       ^
/opt/local/var/macports/build/_opt_macports_sources_ports_latest_llm_llama.cpp/llama.cpp/work/llama.cpp-4508/src/llama-mmap.cpp:196:9: error: use of undeclared identifier 'errno'
        errno = 0;
        ^

[...etc, etc...]

The fix is to simply add an include for <cerrno>. An issue was submitted to upstream, along with a corresponding PR:

• ​Issue 11295 - Compile bug: llama-mmap.cpp: use of errno without including <cerrno>, causes build failures on some systems
• ​PR 11296 - fix: llama-mmap: add include for cerrno

I'll add the fix to the existing PR, encompassing separate build fixes for earlier macOS releases:

• ​PR 27409 - llama.cpp: fix builds for 10.15 and earlier

[Christopher Nielsen <mascguy@…>]

In 1304a7d9aec264b9dd3331f27f7301428c0217b5/macports-ports (master):

llama.cpp: update to 4508; fix builds on 10.15 and earlier

• Explicitly disable OpenMP

Fixes: #71870

• Upstream patch for errno-related build failure on 10.15:

Fixes: #71880

squash

[mascguy (Christopher Nielsen)]

Upstream just accepted and merged the contributed fix, so it should be present in the next release.