Summary:
MyRocks is using jemalloc latest version, not 3.6.0.
Combining multiple versions (3.6.0 in RocksDB and latest in MyRocks)
broke some features -- for example, getting SIGSEGV when heap profiling
was enabled.
This diff switches to use jemalloc latest, if
env variable ROCKSDB_FBCODE_BUILD_WITH_481=1 was set.
My understanding is this env was used by MyRocks only so it would be
safe to change.
Test Plan: building MyRocks then verified jemalloc heap profiling worked
Reviewers: igor, rven, yhchiang, jtolmer, maykov, sdong
Reviewed By: sdong
Subscribers: dhruba
Differential Revision: https://reviews.facebook.net/D43479