Fix LDFLAGS so lexer links (needs -lm for pow()).
Fix LDFLAGS so lexer links (needs -lm for pow()).

patperry/rust-grammar,bleibig/rust-grammar,bleibig/rust-grammar,bleibig/rust-grammar,patperry/rust-grammar,patperry/rust-grammar,bleibig/rust-grammar,patperry/rust-grammar