In hipFree, synchronize owner of memory (#1018)

* In hipFree, if memory is associated with a device, synchronize that device's streams.

This changes the behavior from synchronizing the currently set TLS device.

* All devices sync in hipFree for _appId=-1 case.

* Revert "All devices sync in hipFree for _appId=-1 case."

This reverts commit 1efb34d6a8426661e45bc5f763422a1147aeac10.

* add HIP_SYNC_FREE env var

src/hip_hcc.cpp

@@ -92,6 +92,7 @@ int HIP_EVENT_SYS_RELEASE = 0;
 int HIP_HOST_COHERENT = 1;
 
 int HIP_SYNC_HOST_ALLOC = 1;
+int HIP_SYNC_FREE = 0;
 
 
 int HIP_INIT_ALLOC = -1;
@@ -1279,6 +1280,8 @@ void HipReadEnv() {
 
     READ_ENV_I(release, HIP_SYNC_STREAM_WAIT, 0, "hipStreamWaitEvent will synchronize to host");
 
+    READ_ENV_I(release, HIP_SYNC_FREE, 0,
+               "Force all calls to hipFree to sync all devices and all streams");
 
     READ_ENV_I(release, HIP_HOST_COHERENT, 0,
                "If set, all host memory will be allocated as fine-grained system memory.  This "