Don't use builtin LZMA

[singiamtel]

Don't use builtin LZMA

[singiamtel]

-- Could NOT find LibLZMA (missing: LIBLZMA_INCLUDE_DIR) 
-- LZMA not found. Switching on builtin_lzma option

Well, this seems like a pretty aggressive default by ROOT. I'll specify this variable too

[singiamtel]

/Volumes/build/alice-ci-workdir/alidist-o2_staging/sw/SOURCES/O2/6201/0/Common/Field/src/MagFieldParam.cxx:101:14: error: variable length arrays in C++ are a Clang extension [-Werror,-Wvla-cxx-extension]
  101 |   char cbuff[lgt + 2];
      |              ^~~~~~~

Not sure why this happens, I thought it'd be fixed by the new ROOT