i#975 static DR: Reset flag used for auto-standalone-init (#4394)
i#975 static DR: Reset flag used for auto-standalone-init (#4394)

Resets a flag used to auto-initialize when heap routines are called
without an explicit dr_standalone_init(), enable drdecode and other
use cases.  Without this reset, a prior dr_standalone_exit() can cause
a subsequent crash when using implicit-initialization interfaces.

Issue: #975
AmesianX/dynamorio,AmesianX/dynamorio,AmesianX/dynamorio,AmesianX/dynamorio,AmesianX/dynamorio