fix glog pod install with Xcode 12 (#30372)

Summary:
Today I created a project with RN 0.63 and it failed to **pod install**, and after some investigation I found following error. It's caused by Xcode 12 because it dropped support for 32 bit architectures, but following script sets architecture to armv7 which is 32bit.

This will change architecture to arm64, 64 bit.

```
configure:3727: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/cc -arch armv7 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS14.1.sdk    conftest.c  >&5
clang: error: invalid iOS deployment version 'IPHONEOS_DEPLOYMENT_TARGET=12.0', iOS 10 is the maximum deployment target for 32-bit targets [-Winvalid-ios-deployment-target]
configure:3731: $? = 1
```

## Changelog

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[IOS] [Changed] - fix glog pod install with Xcode 12

Pull Request resolved: https://github.com/facebook/react-native/pull/30372

Test Plan: Create a new project using react-native init, and it'll fail to do pod install. When this change applied, it'll do it successfully.

Reviewed By: fkgozali

Differential Revision: D25957237

Pulled By: PeteTheHeat

fbshipit-source-id: 4ecfaee29da4171fb190352927ec47dbb73fbaa0

scripts/ios-configure-glog.sh

@@ -16,7 +16,7 @@ if [ -z "$CURRENT_ARCH" ] || [ "$CURRENT_ARCH" == "undefined_arch" ]; then
     if [[ "$PLATFORM_NAME" == *"simulator"* ]]; then
         CURRENT_ARCH="x86_64"
     else
-        CURRENT_ARCH="armv7"
+        CURRENT_ARCH="arm64"
     fi
 fi