ci: add a script to install tcc from source on freebsd so it can be run the freebsd job

.github/workflows/freebsd_build_tcc.sh

@@ -0,0 +1,26 @@
+#!/usr/local/bin/bash
+
+## should be run in V's main repo folder!
+
+rm -rf tinycc/
+rm -rf thirdparty/tcc/
+
+pushd .
+
+git clone git://repo.or.cz/tinycc.git
+cd tinycc
+
+./configure --prefix=thirdparty/tcc \
+            --bindir=thirdparty/tcc \
+            --crtprefix=thirdparty/tcc/lib:/usr/lib \
+            --libpaths=thirdparty/tcc/lib:/usr/lib:/lib:/usr/local/lib \
+            --debug
+make
+make install
+
+popd
+
+mv tinycc/thirdparty/tcc thirdparty/tcc
+mv thirdparty/tcc/tcc thirdparty/tcc/tcc.exe
+
+thirdparty/tcc/tcc.exe -v -v