Add .clangd to .gitignore

[michaelortmann]

Found by: michaelortmann Patch by: michaelortmann Fixes:

One-line summary: Add .clangd to .gitignore

Additional description (if needed): For development i use a .clangd file, and i want it to be ignored by git.

Test cases demonstrating functionality (if applicable): If youre curious ;) my .clangd looks like this:

CompileFlags:
  Add: [-Wall, -Wno-deprecated-non-prototype, -I/home/michael/usr/src/eggdrop, -DHAVE_CONFIG_H]