obs-filter: Fix potential symbol clashing on Linux

RNNoise symbols may collide with external ones provided by
libcodec2.so which FFMPEG may pull in automatically. Changing
the visibility of these symbols will guarantee the use of the
internal ones and not pick some (potential incompatible) from
outside.

fixes #3561

plugins/obs-filters/CMakeLists.txt

@@ -20,6 +20,9 @@ if(NOT LIBRNNOISE_FOUND)
 		"rnnoise/src/*.h"
 		"rnnoise/include/*.h")
 	add_definitions(-DCOMPILE_OPUS)
+	if("${CMAKE_SYSTEM_NAME}" MATCHES "Linux")
+		set_property(SOURCE ${rnnoise_SOURCES} PROPERTY COMPILE_FLAGS "-fvisibility=protected")
+	endif()
 	include_directories("rnnoise/include")
 	source_group("rnnoise" FILES ${rnnoise_SOURCES})
 	set(LIBRNNOISE_FOUND TRUE)