emulators/flycast adjust WANTLIB and LIB_DEPENDS

Now that graphics/glslang is provides shared libraries, I would like to
adjust the flycast port.

This inline diff:
- adds SPIRV and vulkan to WANTLIB. graphics/glslang now provides
SPIRV. vulkan is dlopen'ed so ignore the `make port-lib-depends-check'
warning. This is taken from games/fs2open.
- adds COMPILER line for C++
- moves graphics/vulkan-loader from RUN_DEPENDS to LIB_DEPENDS. It
provides the dlopen'ed vulkan. RUN_DEPENDS was incorrect and other
consumers also list it as LIB_DEPENDS.
- bumps REVISION

I tested using vulkan and opengl and confirmed that libvulkan.so.1.1 is
opened using `env LD_DEBUG= flycast' when using the vulkan backend.

ok?

Index: Makefile
===================================================================
RCS file: /cvs/ports/emulators/flycast/Makefile,v
retrieving revision 1.3
diff -u -p -u -p -r1.3 Makefile
--- Makefile 30 Apr 2023 19:39:39 -0000 1.3
+++ Makefile 24 May 2023 23:13:40 -0000
@@ -19,18 +19,22 @@ MAINTAINER = Nam Nguyen <namn@berkeley.e
# Custom NVIDIA and Khronos Group (glslang preprocessor)
PERMIT_PACKAGE = Yes

-WANTLIB += ${COMPILER_LIBCXX} GL SDL2 ao c curl chdr glslang
-WANTLIB += lua${MODLUA_VERSION} m miniupnpc pulse xxhash z zip
+# if running with vulkan backend, dlopen's vulkan in vulkan.hpp
+WANTLIB += ${COMPILER_LIBCXX} GL SDL2 SPIRV ao c curl chdr glslang
+WANTLIB += lua${MODLUA_VERSION} m miniupnpc pulse vulkan xxhash z zip

NO_TEST = Yes

+# C++
+COMPILER = base-clang ports-gcc base-gcc
+
MODULES = devel/cmake \
lang/lua

V = 2.1pl20230303
MASTER_SITES = https://namtsui.com/source/
DISTNAME = flycast-${V}
-REVISION = 0
+REVISION = 1

COMMIT = 27b6bafd0f003c8f8bcd1fb3bfd48a3523b298f5

@@ -41,11 +45,11 @@ USE_WXNEEDED = Yes

MODLUA_VERSION = 5.3

-RUN_DEPENDS = graphics/vulkan-loader
BUILD_DEPENDS = lang/luabridge
LIB_DEPENDS = audio/libao \
devel/sdl2 \
graphics/glslang \
+ graphics/vulkan-loader \
emulators/libchdr \
sysutils/xxhash \
net/curl \