Shared mutex fixes and improvements

* Don't make different shared memory mutexes for different users
* Don't delete (unlink) the shared mutex file if the mutex
  initialization fails. This may mess up other processes that
  are using it. Instead, print a message on how to resolve the
  situation, and then throw an error.

  Note, this situation comes up when debug builds (usually)
  either assert() or otherwise end execution without a proper
  clean up.
* Remove cpplint from shared_mutex code

Change-Id: I5f8ca6150cac5c2405fb97007516da345093f966

include/rocm_smi/rocm_smi.h

@@ -118,6 +118,9 @@ typedef enum {
                                          //!< input
   RSMI_STATUS_UNEXPECTED_DATA,           //!< The data read or provided to
                                          //!< function is not what was expected
+  RSMI_STATUS_RESOURCE_BUSY,             //!< A function timed out trying to
+                                         //!< a resource. This could be a
+                                         //!< mutex time-out.
   RSMI_STATUS_UNKNOWN_ERROR = 0xFFFFFFFF,  //!< An unknown error occurred
 } rsmi_status_t;
 

include/rocm_smi/rocm_smi_device.h

@@ -58,9 +58,7 @@
 #include "rocm_smi/rocm_smi_common.h"
 #include "rocm_smi/rocm_smi.h"
 #include "rocm_smi/rocm_smi_counters.h"
-extern "C" {
-#include "shared_mutex.h"   // NOLINT
-};
+#include "shared_mutex.h"   //NOLINT
 
 namespace amd {
 namespace smi {