linux-alsa: Add ALSA audio input plugin (linux)

Closes jp9000/obs-studio#494

plugins/linux-alsa/CMakeLists.txt

@@ -0,0 +1,34 @@
+project(linux-alsa)
+
+if(DISABLE_ALSA)
+	message(STATUS "ALSA support disabled")
+	return()
+endif()
+
+find_package(ALSA)
+if(NOT ALSA_FOUND AND ENABLE_ALSA)
+	message(FATAL_ERROR "ALSA not found but set as enabled")
+elseif(NOT ALSA_FOUND)
+	message(STATUS "ALSA not found, disabling ALSA plugin")
+	return()
+endif()
+
+include_directories(
+	SYSTEM "${CMAKE_SOURCE_DIR}/libobs"
+	${ALSA_INCLUDE_DIR}
+)
+
+set(linux-alsa_SOURCES
+	linux-alsa.c
+	alsa-input.c
+)
+
+add_library(linux-alsa MODULE
+	${linux-alsa_SOURCES}
+)
+target_link_libraries(linux-alsa
+	libobs
+	${ALSA_LIBRARY}
+)
+
+install_obs_plugin_with_data(linux-alsa data)