Record SourceLocation in exportables.

This will be used by some upcoming work to verify consistency
between 32-bit and 64-bit compilation during the reflection
processs.  Having the SourceLocation available will allow
diagnostics to be more useful.

Bug: 32780232
Bug: 20260865
Bug: 21597073

Test: aosp_x86_64-eng slang/tests, slang/lit-tests,
      RsTest (32-bit, 64-bit)
Change-Id: I1dfee385f5b5a85df8eae9bcb5589c487838c7d7
8 files changed