Don't require breakpad/ffmpeg build directories on Linux

external/crash_reports/breakpad/CMakeLists.txt

@@ -7,10 +7,19 @@
 add_library(external_breakpad INTERFACE IMPORTED GLOBAL)
 add_library(desktop-app::external_breakpad ALIAS external_breakpad)
 
-target_include_directories(external_breakpad SYSTEM
-INTERFACE
+if (LINUX)
+    find_package(PkgConfig REQUIRED)
+    pkg_check_modules(BREAKPAD REQUIRED breakpad)
+    target_include_directories(external_breakpad SYSTEM
+    INTERFACE
+        ${BREAKPAD_INCLUDE_DIRS}
+    )
+else()
+    target_include_directories(external_breakpad SYSTEM
+    INTERFACE
         ${libs_loc}/breakpad/src
-)
+    )
+endif()
 
 if (build_win64)
     set(breakpad_config_add _x64)

external/ffmpeg/CMakeLists.txt

@@ -25,13 +25,23 @@ if (DESKTOP_APP_USE_PACKAGED)
         PkgConfig::SWRESAMPLE
     )
 else()
+    if (LINUX)
+        target_link_static_libraries(external_ffmpeg
+        INTERFACE
+            avformat
+            avcodec
+            swresample
+            swscale
+            avutil
+        )
+    else()
+        set(ffmpeg_lib_loc ${libs_loc}/ffmpeg)
+
         target_include_directories(external_ffmpeg SYSTEM
         INTERFACE
-        ${libs_loc}/ffmpeg
+            ${ffmpeg_lib_loc}
         )
 
-    set(ffmpeg_lib_loc ${libs_loc}/ffmpeg)
-
         target_link_libraries(external_ffmpeg
         INTERFACE
             ${ffmpeg_lib_loc}/libavformat/libavformat.a
@@ -39,11 +49,17 @@ else()
             ${ffmpeg_lib_loc}/libswresample/libswresample.a
             ${ffmpeg_lib_loc}/libswscale/libswscale.a
             ${ffmpeg_lib_loc}/libavutil/libavutil.a
+        )
+    endif()
+
+    target_link_libraries(external_ffmpeg
+    INTERFACE
         $<LINK_ONLY:desktop-app::external_opus>
         $<TARGET_FILE:desktop-app::external_opus>
         $<LINK_ONLY:desktop-app::external_vpx>
         $<TARGET_FILE:desktop-app::external_vpx>
     )
+
     if (APPLE)
         target_link_libraries(external_ffmpeg INTERFACE bz2)
     elseif (LINUX)