Don't generate compile db entry for *.o files

The log message is distracting.

2024/11/11 16:20:06 Unknown file extension .o on file out/soong/.intermediates/external/boringssl/bcm_object/linux_glibc_x86_64/bcm_object.o
2024/11/11 16:20:06 Unknown file extension .o on file out/soong/.intermediates/external/boringssl/bcm_object/linux_glibc_x86/bcm_object.o
2024/11/11 16:20:06 Unknown file extension .o on file out/soong/.intermediates/external/boringssl/bcm_object/windows_x86/bcm_object.o

Bug: N/A
Test: export SOONG_GEN_COMPDB=1; m nothing
Use a LSP (ex: coc-clangd) on vim.

Change-Id: Ie6dd9b13711bae65f6fd6d1a5286307cd0cf2ad3