Switch to PkgConfig for a few things (kind of a hack)

This might actually be an A-OK hack, but I don't like it and will eventually just make some custom FindPkg's that provide stuff directly from PkgConfig without all the weird If hacks.

This gets it to generate on OpenSUSE for me!

CMakeLists.txt

@@ -144,15 +144,28 @@ endif()
 #include(SuperTux/ProvideTinygettext)
 #include(SuperTux/ProvideSDL2_ttf) # add back?
 
+find_package(PkgConfig)
+
 # Find dependencies
 find_package(SDL2 CONFIG REQUIRED)
 #find_package(PNG CONFIG REQUIRED)
 find_package(SDL2_image CONFIG REQUIRED)
 find_package(SDL2_ttf CONFIG REQUIRED)
-find_package(CURL CONFIG REQUIRED)
+find_package(CURL)
 find_package(OpenAL CONFIG REQUIRED)
-find_package(Ogg CONFIG REQUIRED)
-find_package(Vorbis CONFIG REQUIRED)
+find_package(Ogg CONFIG)
+find_package(Vorbis CONFIG)
+if (NOT (Ogg_FOUND OR Vorbis_FOUND))
+	message("OGG (or Vorbis) Not Found! Trying backup")
+	if (PkgConfig_FOUND)
+		pkg_check_modules(Ogg REQUIRED IMPORTED_TARGET ogg)
+		pkg_check_modules(Vorbis REQUIRED IMPORTED_TARGET vorbis vorbisfile)
+		#pkg_check_modules(VorbisFile REQUIRED IMPORTED_TARGET vorbisfile)
+
+	else()
+		message(FATAL_ERROR "Could not find OGG. Giving up")
+	endif()
+endif()
 find_package(glm CONFIG REQUIRED)
 find_package(fmt CONFIG REQUIRED)
 find_package(PhysFS CONFIG REQUIRED)
@@ -247,7 +260,11 @@ if(NOT EMSCRIPTEN)
 	  $<TARGET_NAME_IF_EXISTS:SDL2::SDL2main>
 	  # SDL2
       $<IF:$<TARGET_EXISTS:SDL2::SDL2>,SDL2::SDL2,SDL2::SDL2-static>)
-  target_link_libraries(supertux2 PUBLIC Ogg::ogg Vorbis::vorbis Vorbis::vorbisfile)
+  target_link_libraries(supertux2 PUBLIC
+  	$<IF:$<TARGET_EXISTS:Ogg::ogg>,Ogg:ogg,PkgConfig::Ogg>
+	$<IF:$<TARGET_EXISTS:Vorbis::vorbis>,Vorbis::vorbis Vorbis::vorbisfile,
+		PkgConfig::Vorbis>
+  )
   target_link_libraries(supertux2 PUBLIC CURL::libcurl)
 endif()