[GWP-ASan] Fix typos.

Summary:
Fix two spelling typos and de-indent a guarded #define so that it's
consistent with clang-format.

Reviewers: vitalybuka

Reviewed By: vitalybuka

Subscribers: #sanitizers, llvm-commits

Tags: #sanitizers, #llvm

Differential Revision: https://reviews.llvm.org/D66311

llvm-svn: 369433