Getting Black screenshot using 'gapit screenshot' command while Enable Anti-aliasing(msaa) in game "PUBG MOBILE"

**Environment information:**
- GAPID version: Release version 1.6.1(downloaded from https://github.com/google/gapid/releases, gapid-1.6.1-windows.msi)
- Host OS: Windows 10 Pro
If tracing on Android:
- Android Version: both 9 and 10

**Bug description**

Black screen when using ‘gapit screenshot’ after capturing a game frame trace with Enable Anti-aliasing(msaa).
The screenshot is fine while Disable Anti-aliasing(msaa)
The game API is GLES

**Reproduction steps**
Step 1: When playing game ‘PUBG MOBILE’, in the game settings, graphics enable Anti-Aliasing (Means enable msaa).
Step 2: In command line run
gapit trace -capture-frames 1 -start-defer -out try01.gfxtrace -api gles -serial "XXXX" -uri "android.intent.action.MAIN:com.tencent.tmgp.pubgmhd/com.epicgames.ue4.SplashActivity"
(Note: change serial “XXXX” to be your Android devices)
Step 2: Run the following command to get replay screenshot
gapit screenshot try01.gfxtrace

**Stacktrace**
Not available.

**Screenshots**
If applicable, add screenshots to help explain your problem.

**Additional debugging information**
- Please attach the generated _gapis.log_ and _gapic.log_ files you will find in the temp folder (e.g. /tmp/ on linux). (Not avalilable)
- If using Android: Please attach a full logcat dump (```adb logcat -d > logcat-full.txt```) that contains logs since GAPID was started. (Not avalilable)