Map unknown exit codes to PlatformStatus.PlatformNotAvailable

For example, if the system does not have libdrm.so.2 installed, then
rocmIsEnabled exits with code 127 because of "error while loading
shared libraries: libdrm.so.2: cannot open shared object file: No
such file or directory" which leads to a Python error "ValueError:
127 is not a valid PlatformStatus"

Author: hahnjo

HeterogeneousCore/Common/python/PlatformStatus.py

@@ -7,3 +7,7 @@ class PlatformStatus(enum.IntEnum):
     PlatformNotAvailable = 1    # the platform is not available for this architecture, OS or compiler
     RuntimeNotAvailable = 2     # the runtime could not be initialised
     DevicesNotAvailable = 3     # there are no visible, usable devices
+
+    @classmethod
+    def _missing_(cls, value):
+        return cls.PlatformNotAvailable