[teagba] Make TeaGBA (other than the ARM asm) build on all platforms

deps/teagba/CMakeLists.txt

@@ -1 +1,8 @@
 add_subdirectory(src)
+
+install(
+    DIRECTORY
+        include/teagba
+    DESTINATION
+        include
+)

deps/teagba/src/CMakeLists.txt

@@ -1,18 +1,23 @@
 enable_language(CXX ASM)
 
-set_source_files_properties(gfx.cpp PROPERTIES COMPILE_FLAGS -marm)
-
 add_library(
 	TeaGBA
-		bios.s
-		gba_crt0.s
 		cstartup.cpp
 		gfx.cpp
 )
 
-if(NOT MSVC)
-	target_compile_options(TeaGBA PRIVATE -Wsign-conversion)
-	target_compile_options(TeaGBA PRIVATE -Wconversion)
+if(TURBINE_BUILD_TYPE STREQUAL "GBA")
+	set_source_files_properties(gfx.cpp PROPERTIES COMPILE_FLAGS -marm)
+	target_sources(
+		TeaGBA PRIVATE
+			bios.s
+			gba_crt0.s
+	)
+else()
+	target_sources(
+		TeaGBA PRIVATE
+			bios_stub.cpp
+	)
 endif()
 
 target_include_directories(

deps/teagba/src/bios_stub.cpp

@@ -0,0 +1,22 @@
+/*
+ * Copyright 2016 - 2023 gary@drinkingtea.net
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+// stubs for building TeaGBA for PC targets, for purposes of not having to
+// switch back and forth between builds when editing GBA files
+
+extern "C" {
+
+void teagba_halt() {}
+
+void teagba_stop() {}
+
+void teagba_intrwait(unsigned, unsigned) {}
+
+void teagba_vblankintrwait() {}
+
+}