Fix Base.libllvm_path and jl_get_libllvm don't support non-ASCII char…

…acters in path on Windows (#45126) (#45127)

* Fix jl_get_libllvm_impl to support non-ASCII characters

* Fix jl_get_libllvm_impl to support non-ASCII characters, fix whitespace

* Fix jl_get_libllvm_impl to support non-ASCII characters, fix null and buffer

(cherry picked from commit 6976bac)

src/codegen.cpp

@@ -8927,11 +8927,15 @@ extern "C" JL_DLLEXPORT jl_value_t *jl_get_libllvm_impl(void) JL_NOTSAFEPOINT
     HMODULE mod;
     if (!GetModuleHandleEx(GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS, (LPCSTR)&llvm::DebugFlag, &mod))
         return jl_nothing;
-
-    char path[MAX_PATH];
-    if (!GetModuleFileNameA(mod, path, sizeof(path)))
+    wchar_t path16[MAX_PATH];
+    DWORD n16 = GetModuleFileNameW(mod, path16, MAX_PATH);
+    if (n16 <= 0)
+        return jl_nothing;
+    path16[n16++] = 0;
+    char path8[MAX_PATH * 3];
+    if (!WideCharToMultiByte(CP_UTF8, 0, path16, n16, path8, MAX_PATH * 3, NULL, NULL))
         return jl_nothing;
-    return (jl_value_t*) jl_symbol(path);
+    return (jl_value_t*) jl_symbol(path8);
 #else
     Dl_info dli;
     if (!dladdr((void*)LLVMContextCreate, &dli))