Don't include the Age in the UUID for CvRecordPdb70 UUID records in minidump...

Don't include the Age in the UUID for CvRecordPdb70 UUID records in minidump files for Apple vendors.

The CvRecordPdb70 structure looks like:

struct CvRecordPdb70 {
  uint8_t Uuid[16];
  llvm::support::ulittle32_t Age;
  // char PDBFileName[];
};
We were including the "Age" in the UUID for Apple vedors which caused us to not be able to match the UUID to built binaries. The "Age" field is set to zero in breakpad minidump files for Apple targets. 

Differential Revision: https://reviews.llvm.org/D51442

llvm-svn: 340966