enable UBSAN macro in TARGETS

Summary:
simply enable the macro in internal build, it wont hurt other sanitizers and will fix UBSAN issues
Closes https://github.com/facebook/rocksdb/pull/2625

Differential Revision: D5475897

Pulled By: IslamAbdelRahman

fbshipit-source-id: 262c6fd5de3c1906f4b29e55b39110f125f41057

TARGETS

@@ -18,6 +18,7 @@ rocksdb_compiler_flags = [
   "-DROCKSDB_SUPPORT_THREAD_LOCAL",
   "-DHAVE_SSE42",
   "-DOS_LINUX",
+  "-DROCKSDB_UBSAN_RUN",
   # Flags to enable libs we include
   "-DSNAPPY",
   "-DZLIB",

buckifier/targets_cfg.py

@@ -22,6 +22,7 @@ rocksdb_compiler_flags = [
   "-DROCKSDB_SUPPORT_THREAD_LOCAL",
   "-DHAVE_SSE42",
   "-DOS_LINUX",
+  "-DROCKSDB_UBSAN_RUN",
   # Flags to enable libs we include
   "-DSNAPPY",
   "-DZLIB",