Fix JuliaLang#10829

The change in 11a0f43 made the assumption that `handle->errmsg`
would be initialized to NUL.  This is true within julia itself, but
BinDeps violates this assumption.  The current commit changes things
to fix the memory leak at its actual source, in `jl_load_dynamic_library_`.

src/dlload.c

@@ -63,14 +63,10 @@ DLLEXPORT int jl_uv_dlopen(const char *filename, jl_uv_libhandle lib_, unsigned
 #endif
  );
  if (lib->handle) {
- if (lib->errmsg)
- free(lib->errmsg);
  lib->errmsg = NULL;
  return 0;
  }
  else {
- if (lib->errmsg)
- free(lib->errmsg);
  lib->errmsg = strdup(dlerror());
  return -1;
  }
@@ -124,6 +120,10 @@ static uv_lib_t *jl_load_dynamic_library_(const char *modname, unsigned flags, i
  snprintf(path, PATHBUF, "%s%s%s", dl_path, modname, ext);
  else
  snprintf(path, PATHBUF, "%s" PATHSEPSTRING "%s%s", dl_path, modname, ext);
+ if (handle->errmsg) {
+ free(handle->errmsg);
+ handle->errmsg = NULL;
+ }
  error = jl_uv_dlopen(path, handle, flags);
  if (!error) goto done;
  }
@@ -136,13 +136,21 @@ static uv_lib_t *jl_load_dynamic_library_(const char *modname, unsigned flags, i
  handle->handle = NULL;
  /* try loading from standard library path */
  snprintf(path, PATHBUF, "%s%s", modname, ext);
+ if (handle->errmsg) {
+ free(handle->errmsg);
+ handle->errmsg = NULL;
+ }
  error = jl_uv_dlopen(path, handle, flags);
  if (!error) goto done;
  }
 
 #if defined(__linux__) || defined(__FreeBSD__)
  {
  const char *soname = jl_lookup_soname(modname, strlen(modname));
+ if (handle->errmsg) {
+ free(handle->errmsg);
+ handle->errmsg = NULL;
+ }
  error = (soname==NULL) || jl_uv_dlopen(soname, handle, flags);
  if (!error) goto done;
  }