Validate ResStringPool_header.styleCount

This is to prevent potential out-of-bounds reads beyond the bounds of
the string pool chunk.

Bug: 462431486
Flag: EXEMPT CVE_FIX
Test: atest libandroidfw_tests
Test: Manual: An APK with invalid styleCount failed to install
Cherrypick-From: https://googleplex-android-review.googlesource.com/q/commit:62cb59ae21e6b27e510ee3af58d0df8ad9bc70a7
Cherrypick-From: https://googleplex-android-review.googlesource.com/q/commit:5d8844413d903d3b526708e9b8dd73b886b68173
Merged-In: If846443caa357197cd393e85c1461119b8264eb4
Change-Id: If846443caa357197cd393e85c1461119b8264eb4