Improve cmake crashpad/breakpad discovery, compilation & installation under Unix (#1184)

* Clean up Crashpad library discovery code

* Find and install Breakpad binary

* Copy crashpad_handler and minidum_stackwalk POST_BUILD (macOS only)

* Install crashpad_handler and minidum_stackwalk for AppImage

app/CMakeLists.txt

@@ -176,13 +176,13 @@ if (GoogleCrashpad_FOUND)
     ${OLIVE_TARGET}
     PRIVATE
     ${CRASHPAD_INCLUDE_DIRS}
-    )
+  )
 
   target_link_libraries(
     ${OLIVE_TARGET}
     PRIVATE
     ${CRASHPAD_LIBRARIES}
-    )
+  )
 
   set(OLIVE_CRASH_TARGET "olive-crashhandler")
 
@@ -221,14 +221,21 @@ if (GoogleCrashpad_FOUND)
     ${CRASHPAD_LIBRARIES}
   )
 
+  set(CRASHPAD_HANDLER "crashpad_handler${CMAKE_EXECUTABLE_SUFFIX}")
+  set(MINIDUMP_STACKWALK "minidump_stackwalk${CMAKE_EXECUTABLE_SUFFIX}")
+
   if(UNIX AND NOT APPLE)
     install(TARGETS ${OLIVE_TARGET} ${OLIVE_CRASH_TARGET} RUNTIME DESTINATION bin)
+    install(PROGRAMS ${CRASHPAD_LIBRARY_DIRS}/${CRASHPAD_HANDLER} DESTINATION bin)
+    install(PROGRAMS ${BREAKPAD_BIN_DIR}/${MINIDUMP_STACKWALK} DESTINATION bin)
   endif()
 
   if(APPLE)
-    # Move crash handler program inside Mac app bundle
+    # Move crash handler executables inside Mac app bundle
     add_custom_command(TARGET ${OLIVE_CRASH_TARGET} POST_BUILD
-        COMMAND ${CMAKE_COMMAND} -E copy ${OLIVE_CRASH_TARGET} $<TARGET_FILE_DIR:${OLIVE_TARGET}>
+      COMMAND ${CMAKE_COMMAND} -E copy_if_different ${OLIVE_CRASH_TARGET} $<TARGET_FILE_DIR:${OLIVE_TARGET}>
+      COMMAND ${CMAKE_COMMAND} -E copy_if_different ${CRASHPAD_LIBRARY_DIRS}/${CRASHPAD_HANDLER} $<TARGET_FILE_DIR:${OLIVE_TARGET}>
+      COMMAND ${CMAKE_COMMAND} -E copy_if_different ${BREAKPAD_BIN_DIR}/${MINIDUMP_STACKWALK} $<TARGET_FILE_DIR:${OLIVE_TARGET}>
     )
   endif()
 endif()