Make PIC native code architecture independent

The size of size_t depends on the architecture (32-bit vs 64-bit).
This CL replaces all occurrences if size_t in the memory layout of PIC
nonces with int32_t.  int32_t is more than large enough and it is
guaranteed to be 4 bytes wide in all architectures.

Flag: EXEMPT bug-fix
Bug: 396674280
Test: atest
 * FrameworksCoreTests:PropertyInvalidatedCacheTests
 * FrameworksCoreTests:IpcDataCacheTest
 * CtsOsTestCases:IpcDataCacheTest
Change-Id: I281ecd59b506f64e625890d496d6dede4e178460