Expose ROCr build ID.

Adds HSA_AMD_SYSTEM_INFO_BUILD_VERSION=0x200 to hsa_system_info_t.
This returns a const char* pointing at the build string (git describe).

Change-Id: I73e6612482bf6ffc4037fd365808eb9211a650ad

runtime/hsa-runtime/inc/hsa.h

@@ -476,7 +476,11 @@ typedef enum {
    * implementation. An extension with an ID of @p i is supported if the bit at
    * position @p i is set. The type of this attribute is uint8_t[128].
    */
-  HSA_SYSTEM_INFO_EXTENSIONS = 7
+  HSA_SYSTEM_INFO_EXTENSIONS = 7,
+  /**
+  * String containing the ROCr build identifier.
+  */
+  HSA_AMD_SYSTEM_INFO_BUILD_VERSION = 0x200
 } hsa_system_info_t;
 
 /**