Revert "[ARM] Promote small global constants to constant pools"

Breaks Android tests by introducing text relocations to ARM binaries.

http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux/builds/25362/steps/run%20asan%20lit%20tests%20%5Barm%2Fbullhead-userdebug%2FMTC20F%5D/logs/stdio

llvm-svn: 281526