Fix #10865, Windows julia segfaulting without sys.dll

use LocalFree on Windows instead of free

also test this on appveyor

appveyor.yml

@@ -50,4 +50,5 @@ build_script:
 
 test_script:
  - usr\bin\julia -e "versioninfo()"
+ - copy usr\lib\julia\sys.ji local.ji && usr\bin\julia -J local.ji -e "true" && del local.ji
  - cd test && ..\usr\bin\julia runtests.jl all

src/dlload.c

@@ -121,7 +121,11 @@ static uv_lib_t *jl_load_dynamic_library_(const char *modname, unsigned flags, i
  else
  snprintf(path, PATHBUF, "%s" PATHSEPSTRING "%s%s", dl_path, modname, ext);
  if (handle->errmsg) {
+#ifdef _OS_WINDOWS_
+ LocalFree((void*)handle->errmsg);
+#else
  free(handle->errmsg);
+#endif
  handle->errmsg = NULL;
  }
  error = jl_uv_dlopen(path, handle, flags);
@@ -137,7 +141,11 @@ static uv_lib_t *jl_load_dynamic_library_(const char *modname, unsigned flags, i
  /* try loading from standard library path */
  snprintf(path, PATHBUF, "%s%s", modname, ext);
  if (handle->errmsg) {
+#ifdef _OS_WINDOWS_
+ LocalFree((void*)handle->errmsg);
+#else
  free(handle->errmsg);
+#endif
  handle->errmsg = NULL;
  }
  error = jl_uv_dlopen(path, handle, flags);