Call Abort() on aborted operations.

This change was already reviewed, merged and reverted, so I'm skipping
the review step this time.

Change-Id: I47a11e366fcf8d8f877e7d21fc1c8257cec3d51d
diff --git a/google_keymaster.cpp b/google_keymaster.cpp
index fd4b345..582a03b 100644
--- a/google_keymaster.cpp
+++ b/google_keymaster.cpp
@@ -273,7 +273,10 @@
     OpTableEntry* entry = FindOperation(op_handle);
     if (entry == NULL)
         return KM_ERROR_INVALID_OPERATION_HANDLE;
+    keymaster_error_t error = entry->operation->Abort();
     DeleteOperation(entry);
+    if (error != KM_ERROR_OK)
+        return error;
     return KM_ERROR_OK;
 }