va_trace: annotate internal functions with DLL_HIDDEN

[evelikov]

Annotate the following functions with DLL_HIDDEN:

• va_errorMessage
• va_infoMessage
• va_parseConfig
• va_TraceEvent
• va_TraceEventBuffers
• va_TraceStatus

The APIs have been used solely within libva.so ever since they were introduced. As such we can safely hide it was never used externally and it's not part of the public API.

-- Couple of the above (aka va_TraceEvent*) were added recently with https://github.com/intel/libva/pull/552, others like va_TraceStatus have been around since 2019, while the rest have been a thing for even longer.

@lindongw to double-check the va_TraceEvent symbols that you've added are meant to be internal-only, correct?

[evelikov]

@XinfengZhang @dvrogozh these are safe to backport to 2.16

[lindongw]

yes, va_TraceEvent is internal funcation

[evelikov]

@XinfengZhang @dvrogozh ping?

[evelikov]

@XinfengZhang can we merge this?