[llvm-mca] Fixed a problem caused by an invalid use of a processor resource mask in the Scheduler.

The lambda functions used by method ResourceManager::mustIssueImmediately() was
incorrectly truncating masks of buffered processor resources to 32-bit quantities.
The invalid mask values were then used to access a map of processor
resource descriptors.

Fixes PR37643.

llvm-svn: 333692