thirdparty: add script to build libgc on FreeBSD/amd64 (#24717)

thirdparty/build_scripts/thirdparty-freebsd-amd64_bdwgc.sh

@@ -0,0 +1,59 @@
+#!/usr/bin/env bash
+
+set -e
+
+if ! test -f vlib/v/compiler_errors_test.v; then
+  echo "this script should be run in V's main repo folder!"
+  exit 1
+fi
+  
+export CURRENT_SCRIPT_PATH=$(realpath "$0")
+
+export CC="${CC:-gcc}"
+export TCC_FOLDER="${TCC_FOLDER:-thirdparty/tcc}"
+export LIBGC_COMMIT="${LIBGC_COMMIT:-master}"
+mkdir -p $TCC_FOLDER/lib/
+
+echo "          CC: $CC"
+echo "  TCC_FOLDER: $TCC_FOLDER"
+echo "LIBGC_COMMIT: $LIBGC_COMMIT"
+echo ===============================================================
+
+rm -rf bdwgc/
+
+pushd .
+git clone https://github.com/ivmai/bdwgc
+cd bdwgc/
+
+git checkout $LIBGC_COMMIT
+export LIBGC_COMMIT_FULL_HASH=$(git rev-parse HEAD)
+
+./autogen.sh
+
+CC=$CC CFLAGS='-Os -mtune=generic -fPIC' LDFLAGS='-Os -fPIC' ./configure \
+	--disable-dependency-tracking \
+	--disable-docs \
+	--enable-handle-fork=yes \
+	--enable-rwlock \
+	--enable-threads=posix \
+	--enable-static \
+	--enable-shared=no \
+	--enable-parallel-mark \
+	--enable-single-obj-compilation \
+	--enable-gc-debug \
+	--with-libatomic-ops=yes \
+	--enable-sigrt-signals \
+	--enable-mmap
+
+make
+
+popd
+
+cp bdwgc/.libs/libgc.a         $TCC_FOLDER/lib/libgc.a
+
+date                         > $TCC_FOLDER/lib/libgc_build_on_date.txt
+echo $LIBGC_COMMIT_FULL_HASH > $TCC_FOLDER/lib/libgc_build_source_hash.txt
+uname -a                     > $TCC_FOLDER/lib/libgc_build_machine_uname.txt
+
+ls -la $TCC_FOLDER/lib/libgc.a
+echo "Done compiling libgc, at commit $LIBGC_COMMIT , full hash: $LIBGC_COMMIT_FULL_HASH . The static library is in $TCC_FOLDER/lib/libgc.a "