cmake: Fix enabling PulseAudio monitoring

Also adds a warning if null monitoring is "enabled".

CMakeLists.txt

@@ -59,6 +59,7 @@ elseif(OS_MACOS)
 elseif(OS_POSIX)
   option(LINUX_PORTABLE "Build portable version (Linux)" OFF)
   option(USE_XDG "Utilize XDG Base Directory Specification (Linux)" ON)
+  option(ENABLE_PULSEAUDIO "Enable PulseAudio support" ON)
   if(OS_LINUX)
     option(ENABLE_WAYLAND "Enable building with support for Wayland (Linux)" ON)
     option(BUILD_FOR_PPA "Build for PPA distribution" OFF)

libobs/CMakeLists.txt

@@ -399,6 +399,7 @@ elseif(OS_POSIX)
 
     target_link_libraries(libobs PRIVATE ${PULSEAUDIO_LIBRARY})
   else()
+    obs_status(WARNING "-> No audio backend found - audio monitoring disabled")
     target_sources(libobs PRIVATE audio-monitoring/null/null-audio-monitoring.c)
   endif()
 

plugins/linux-pulseaudio/CMakeLists.txt

@@ -1,7 +1,5 @@
 project(linux-pulseaudio)
 
-option(ENABLE_PULSEAUDIO "Enable PulseAudio support" ON)
-
 if(NOT ENABLE_PULSEAUDIO)
   obs_status(DISABLED "linux-pulseaudio")
   return()