Add minidump_extensions.h

compat/non_win/dbghelp.h

Index: compat/non_win/dbghelp.h
diff --git a/compat/non_win/dbghelp.h b/compat/non_win/dbghelp.h
index 85cf4ccbba345a58cf9a67e88afcef8bd300acec..b0d66995b3d38d020b22d0db599a0e17f181b5b3 100644
--- a/compat/non_win/dbghelp.h
+++ b/compat/non_win/dbghelp.h
@@ -404,12 +404,11 @@ struct __attribute__((packed, aligned(4))) MINIDUMP_EXCEPTION {
   //! \brief The top-level exception code identifying the exception, in
   //!     operating system-specific values.
   //!
-  //! For Mac OS X minidumps, this will be a value of
-  //! crashpad::MinidumpExceptionCodeMac, which corresponds to an `EXC_*`
-  //! exception type. `EXC_CRASH` will not appear here for exceptions processed
-  //! as `EXC_CRASH` when generated from another preceding exception: the
-  //! original exception code will appear instead. The exception type as it was
-  //! received will appear at index 0 of #ExceptionInformation.
+  //! For Mac OS X minidumps, this will be an \ref EXC_x "EXC_*" exception type,
+  //! such as `EXC_BAD_ACCESS`. `EXC_CRASH` will not appear here for exceptions
+  //! processed as `EXC_CRASH` when generated from another preceding exception:
+  //! the original exception code will appear instead. The exception type as it
+  //! was received will appear at index 0 of #ExceptionInformation.
   //!
   //! \note This field is named ExceptionCode, but what is known as the
   //!     “exception code” on Mac OS X/Mach is actually stored in the