meson: build libEGL

This is based heavily on Daniel Stone's work for the same, rebased on
master and with a number of TODO's fixed.

This does not implement glvnd (which is coming in a later patch)

Meson builds egl slightly differently than autotools, namely it doesn't
build an intermediate shared library. It doesn't do this because meson
doesn't have problems with the name of the library being dynamically
generated, so the glvnd and non-glvnd code can follow the same path.

v2: - Don't reuse variable (Eric E.)

Signed-off-by: Dylan Baker <dylanx.c.baker@intel.com>
Tested-by: Eric Engestrom <eric.engestrom@imgtec.com>
Reviewed-by: Daniel Stone <daniels@collabora.com>
diff --git a/meson.build b/meson.build
index a8bcaf7..92b875b 100644
--- a/meson.build
+++ b/meson.build
@@ -130,16 +130,20 @@
 # TODO: other OSes
 with_dri_platform = 'drm'
 
-# TODO: there are more platforms required for non-vulkan drivers
+# TODO: android platform
 with_platform_wayland = false
 with_platform_x11 = false
 with_platform_drm = false
+with_platform_surfaceless = false
+egl_native_platform = ''
 _platforms = get_option('platforms')
 if _platforms != ''
   _split = _platforms.split(',')
   with_platform_x11 = _split.contains('x11')
   with_platform_wayland = _split.contains('wayland')
   with_platform_drm = _split.contains('drm')
+  with_platform_surfaceless = _split.contains('surfaceless')
+  egl_native_platform = _split[0]
 endif
 
 with_gbm = get_option('gbm')
@@ -154,6 +158,27 @@
   with_gbm = false
 endif
 
+_egl = get_option('egl')
+if _egl == 'auto'
+  with_egl = with_dri and with_shared_glapi and egl_native_platform != ''
+elif _egl == 'yes'
+  if not with_dri
+    error('EGL requires dri')
+  elif not with_shared_glapi
+    error('EGL requires shared-glapi')
+  elif egl_native_platform == ''
+    error('No platforms specified, consider -Dplatforms=drm,x11 at least')
+  endif
+  with_egl = true
+else
+  with_egl = false
+endif
+
+# TODO: or virgl
+if with_egl and with_gallium_radeonsi and not (with_platform_drm or with_platform_surfaceless)
+  error('RadeonSI requires drm or surfaceless platform when using EGL')
+endif
+
 pre_args += '-DGLX_USE_TLS'
 with_glx = get_option('glx')
 if with_glx != 'disabled'
@@ -228,7 +253,7 @@
   error('Vulkan drivers require dri3 for X11 support')
 endif
 if with_dri or with_gallium
-  if with_glx == 'disabled' # TODO: or egl
+  if with_glx == 'disabled' and not with_egl
     error('building dri or gallium drivers require at least one window system')
   endif
 endif
@@ -250,6 +275,7 @@
                         with_gallium_omx or with_gallium_va)
 endif
 
+gl_pkgconfig_c_flags = []
 if with_platform_x11
   if with_any_vk or (with_glx == 'dri' and with_dri_platform == 'drm')
     pre_args += '-DHAVE_X11_PLATFORM'
@@ -269,6 +295,18 @@
       pre_args += '-DGLX_USE_DRM'
     endif
   endif
+else
+  pre_args += '-DMESA_EGL_NO_X11_HEADERS'
+  gl_pkgconfig_c_flags += '-DMESA_EGL_NO_X11_HEADERS'
+endif
+if with_platform_drm
+  if with_egl and not with_gbm
+    error('EGL drm platform requires gbm')
+  endif
+  pre_args += '-DHAVE_DRM_PLATFORM'
+endif
+if with_platform_surfaceless
+  pre_args += '-DHAVE_SURFACELESS_PLATFORM'
 endif
 
 prog_python2 = find_program('python2')
@@ -646,18 +684,22 @@
 
 # TODO: symbol mangling
 
-# TODO: egl configuration
-
 if with_platform_wayland
   prog_wl_scanner = find_program('wayland-scanner')
   dep_wl_protocols = dependency('wayland-protocols', version : '>= 1.8')
   dep_wayland_client = dependency('wayland-client', version : '>=1.11')
   dep_wayland_server = dependency('wayland-server', version : '>=1.11')
+  wayland_dmabuf_xml = join_paths(
+    dep_wl_protocols.get_pkgconfig_variable('pkgdatadir'), 'unstable',
+    'linux-dmabuf', 'linux-dmabuf-unstable-v1.xml'
+  )
+  pre_args += ['-DHAVE_WAYLAND_PLATFORM', '-DWL_HIDE_DEPRECATED']
 else
   prog_wl_scanner = []
   dep_wl_protocols = []
   dep_wayland_client = []
   dep_wayland_server = []
+  wayland_dmabuf_xml = ''
 endif
 
 dep_x11 = []
@@ -674,6 +716,7 @@
 dep_xcb_dri3 = []
 dep_xcb_present = []
 dep_xcb_sync = []
+dep_xcb_xfixes = []
 dep_xshmfence = []
 if with_platform_x11
   if with_glx == 'dri' and with_dri_platform == 'drm'
@@ -701,21 +744,19 @@
     dep_dri2proto = dependency('dri2proto', version : '>= 2.8')
     dep_glproto = dependency('glproto', version : '>= 1.4.14')
   endif
+  if with_egl
+    dep_xcb_xfixes = dependency('xcb-xfixes')
+  endif
 endif
 
-# TODO: platforms for !vulkan
-
 # TODO: osmesa
 
-# TODO: egl
-
 # TODO: vallium G3DVL
 
 # TODO: nine
 
 # TODO: clover
 
-# TODO: egl sans x11
 # TODO: gallium tests
 
 # TODO: various libdirs
@@ -744,6 +785,28 @@
 
 inc_include = include_directories('include')
 
+gl_priv_reqs = [
+  'x11', 'xext', 'xdamage >= 1.1', 'xfixes', 'x11-xcb', 'xcb',
+  'xcb-glx >= 1.8.1', 'libdrm >= 2.4.75',
+]
+if dep_xf86vm != [] and dep_xf86vm.found()
+  gl_priv_reqs += 'xf86vm'
+endif
+if with_dri_platform == 'drm'
+  gl_priv_reqs += 'xcb-dri2 >= 1.8'
+endif
+
+gl_priv_libs = []
+if dep_thread.found()
+  gl_priv_libs += ['-lpthread', '-pthread']
+endif
+if dep_m.found()
+  gl_priv_libs += '-lm'
+endif
+if dep_dl.found()
+  gl_priv_libs += '-ldl'
+endif
+
 pkg = import('pkgconfig')
 
 subdir('include')