Revert "libcaca: use pkg-config --static"

This reverts commit 42975a1b0c881a800a162a99bf8f57d0996ac0b8.
really fix libcaca

libcaca directly uses GL and GLU symbols. Mark them explicitly.

Fix #511 again.

Signed-off-by: Timothy Gu <timothygu99@gmail.com>