The arm, aarch64, and shared instr and opnd create macro files were already pure-public, so we rename them to add _api.h to the end: core/ir/instr_create_shared_api.h, core/ir/arm/instr_create_api.h, core/ir/aarch64/instr_create_api.h,
For x86, we also rename core/ir/x86/instr_create_api.h, but since we have some private macros, we also create a new instr_create_shared.h and x86/instr_create.h for those. The core includes instr_create_shared.h now.
Replaces the handful of dcontext_t types with void*.
Issue: #3092 (closed)