Set path to libc for openbsd.

Author: euantorano

compiler/evalffi.nim

@@ -17,6 +17,8 @@ when defined(windows):
   const libcDll = "msvcrt.dll"
 elif defined(linux):
   const libcDll = "libc.so(.6|.5|)"
+elif defined(openbsd):
+  const libcDll = "/usr/lib/libc.so(.95.1|)"
 elif defined(bsd):
   const libcDll = "/lib/libc.so.7"
 elif defined(osx):