tests/vm/freebsd: Add additional library paths for libfdt

libfdt is installed in /usr/local on FreeBSD, and since this
library does not have a pkg-config file, we have to specify the
paths manually. This way we can avoid that Meson has to recompile
the dtc subproject each time.

Message-ID: <20231016161053.39150-1-thuth@redhat.com>
Reviewed-by: Warner Losh <imp@bsdimp.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

tests/vm/freebsd

@@ -38,8 +38,9 @@ class FreeBSDVM(basevm.BaseVM):
         cd $(mktemp -d /home/qemu/qemu-test.XXXXXX);
         mkdir src build; cd src;
         tar -xf /dev/vtbd1;
-        cd ../build
-        ../src/configure --python=python3.9 {configure_opts};
+        cd ../build;
+        ../src/configure --python=python3.9  --extra-ldflags=-L/usr/local/lib \
+                         --extra-cflags=-I/usr/local/include {configure_opts};
         gmake --output-sync -j{jobs} {target} {verbose};
     """