Log Message:
nspr: Update to 4.27

Changelog:
NSPR 4.27 contains the following changes:
- The macOS platform code for shared library loading was
   changed to support macOS 11.
   If the absolute path parameter given to PR_LoadLibrary
   begins with either /System/ or /usr/lib/ then no test is
   performed if the library exists at a file.
- An include statement for a Windows system library header
   was added