vulkan: Initial Vulkan support!

This work was done by Jacob Lifshay and Mark Callow; I'm just merging it
into revision control.

configure.in

@@ -2401,6 +2401,62 @@ CheckEmscriptenGLES()
     fi
 }
 
+dnl Check to see if Vulkan surface support is desired
+AC_ARG_ENABLE(video-vulkan,
+AC_HELP_STRING([--enable-video-vulkan], [include Vulkan surface support [[default=yes]]]),
+              , enable_video_vulkan=yes)
+
+dnl Find Vulkan Header
+CheckVulkan()
+{
+    have_vulkan_hdr=no
+    if test x$enable_video = xyes -a x$enable_video_vulkan = xyes; then
+        case "$host" in
+            *-*-androideabi*)
+                AC_TRY_COMPILE([
+                  #if defined(__ANDROID__) && defined(__ARM_EABI__) && !defined(__ARM_ARCH_7A__)
+                  #error Vulkan doesn't work on this configuration
+                  #endif
+                  int main()
+                  {
+                     return 0;
+                  }
+                ],[
+                    enable_video_vulkan=no
+                ],[
+                ])
+                ;;
+            *)
+                ;;
+        esac
+        if test x$enable_video_vulkan = xno; then
+            # For reasons I am totally unable to see, I get an undefined macro error if
+            # I put this in the AC_TRY_COMPILE.
+            AC_MSG_WARN([Sorry, Vulkan does not work on this configuration.])
+        fi
+        if test x$enable_video_vulkan = xyes; then
+            vsdk_include_dir="${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="$save_CPPFLAGS"
+        fi
+    fi
+    if test x$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 
+            EXTRA_CFLAGS="$EXTRA_CFLAGS -I$vsdk_include_dir"
+        fi
+        AC_DEFINE(SDL_VIDEO_VULKAN_SURFACE, 1, [ ])
+        SUMMARY_video="${SUMMARY_video} vulkan"
+    fi
+}
+
 dnl See if we can use the new unified event interface in Linux 2.4
 CheckInputEvents()
 {
@@ -3230,6 +3286,7 @@ case "$host" in
         CheckKMSDRM
         CheckOpenGLX11
         CheckOpenGLESX11
+        CheckVulkan
         CheckMir
         CheckWayland
         CheckLibUDev
@@ -3375,6 +3432,7 @@ case "$host" in
         CheckWINDOWS
         CheckWINDOWSGL
         CheckWINDOWSGLES
+        CheckVulkan
         CheckDIRECTX
 
         # Set up the core platform files
@@ -3559,6 +3617,7 @@ AC_HELP_STRING([--enable-render-d3d], [enable the Direct3D render driver [[defau
         CheckDummyAudio
         CheckDLOPEN
         CheckPTHREAD
+        CheckVulkan
 
         # Set up files for the audio library
         if test x$enable_audio = xyes; then
@@ -3621,6 +3680,9 @@ AC_HELP_STRING([--enable-render-d3d], [enable the Direct3D render driver [[defau
         EXTRA_LDFLAGS="$EXTRA_LDFLAGS -Wl,-framework,OpenGLES"
         EXTRA_LDFLAGS="$EXTRA_LDFLAGS -Wl,-framework,QuartzCore"
         EXTRA_LDFLAGS="$EXTRA_LDFLAGS -Wl,-framework,UIKit"
+        if test x$ac_cv_header_vulkan_vulkan_h = xyes; then
+            EXTRA_LDFLAGS="$EXTRA_LDFLAGS -Wl,-framework,QuartzCore"
+        fi
         ;;
     *-*-darwin* )
         # This could be either full "Mac OS X", or plain "Darwin" which is
@@ -3642,6 +3704,7 @@ AC_HELP_STRING([--enable-render-d3d], [enable the Direct3D render driver [[defau
         CheckX11
         CheckMacGL
         CheckOpenGLX11
+        CheckVulkan
         CheckPTHREAD
 
         # Set up files for the audio library
@@ -3695,6 +3758,9 @@ AC_HELP_STRING([--enable-render-d3d], [enable the Direct3D render driver [[defau
         EXTRA_LDFLAGS="$EXTRA_LDFLAGS -Wl,-framework,Cocoa"
         EXTRA_LDFLAGS="$EXTRA_LDFLAGS -Wl,-framework,Carbon"
         EXTRA_LDFLAGS="$EXTRA_LDFLAGS -Wl,-framework,IOKit"
+        if test x$ac_cv_header_vulkan_vulkan_h = xyes; then
+            EXTRA_LDFLAGS="$EXTRA_LDFLAGS -Wl,-framework,QuartzCore"
+        fi
         ;;
     *-nacl|*-pnacl)
         ARCH=nacl