Get Odin compiling and produced exe's running on FreeBSD

core/dynlib/lib_unix.odin

@@ -1,4 +1,4 @@
-// +build linux, darwin
+// +build linux, darwin, freebsd
 package dynlib
 
 import "core:os"
@@ -18,4 +18,4 @@ symbol_address :: proc(library: Library, symbol: string) -> (ptr: rawptr, found:
     ptr = os.dlsym(rawptr(library), symbol);
     found = ptr != nil;
     return;
-}
+}