We use the SDL Vulkan headers

test/configure.in

@@ -179,25 +179,6 @@ AC_SUBST(GLESLIB)
 AC_SUBST(GLES2LIB)
 AC_SUBST(XLIB)
 
-dnl Check for Vulkan Header
-have_vulkan_hdr=no
-vsdk_include_dir="${VULKAN_SDK}/include"
-vulkan_header="vulkan/vulkan.h"
-save_CPPFLAGS="$CPPFLAGS"
-CPPFLAGS="${save_CPPFLAGS} -I$vsdk_include_dir"
-AC_CHECK_HEADER($vulkan_header,
-                have_vulkan_hdr=yes,
-                have_vulkan_hdr=no)
-CPPFLAGS="$save_CPPFLAGS"
-if test x$have_vulkan_hdr = xyes; then
-    # vulkan.h has been found in either $VULKAN_SDK/include or along the
-    # the standard include path. Unfortunately there seems no easy
-    # way to find out which, so...
-    if test -n "$VULKAN_SDK" -a -f "$vsdk_include_dir/$vulkan_header"; then 
-        CFLAGS="$CFLAGS -I$vsdk_include_dir"
-    fi
-fi
-
 dnl Check for SDL_ttf
 AC_CHECK_LIB(SDL2_ttf, TTF_Init, have_SDL_ttf=yes)
 if test x$have_SDL_ttf = xyes; then