Xserver compilation error with headers provided by libglvnd 1.2

mesa/mesa!2179 (merged)
These changes will be in mesa-19.2.2

meson build:

[333/805] Compiling C object 'glamor/27c065b@@glamor@sta/glamor.c.o'.
FAILED: glamor/27c065b@@glamor@sta/glamor.c.o
/usr/bin/clang -Iglamor/27c065b@@glamor@sta -Iglamor -I../xserver/glamor -IXext -I../xserver/Xext -IXi -I../xserver/Xi -Icomposite -I../xserver/composite -Idamageext -I../xserver/damageext -Iexa -I../xserver/exa -Ifb -I../xserver/fb -Imi -I../xserver/mi -Imiext/damage -I.
./xserver/miext/damage -Imiext/shadow -I../xserver/miext/shadow -Imiext/sync -I../xserver/miext/sync -Idbe -I../xserver/dbe -Idri3 -I../xserver/dri3 -Iinclude -I../xserver/include -Ipresent -I../xserver/present -Irandr -I../xserver/randr -Irender -I../xserver/render -Ixfi
xes -I../xserver/xfixes -I/usr/include/X11/dri -I/usr/include/pixman-1 -I/usr/include/freetype2 -I/usr/include/libpng16 -I/usr/include/harfbuzz -I/usr/include/glib-2.0 -I/usr/lib/glib-2.0/include -Xclang -fcolor-diagnostics -pipe -D_FILE_OFFSET_BITS=64 -Wall -Winvalid-pch
 -std=gnu99 -O3 -DHAVE_DIX_CONFIG_H -fno-strict-aliasing -fvisibility=hidden -Wall -Wpointer-arith -Wmissing-declarations -Wformat=2 -Wstrict-prototypes -Wmissing-prototypes -Wnested-externs -Wbad-function-cast -Wold-style-definition -Wunused -Wuninitialized -Wshadow -Wmi
ssing-noreturn -Wmissing-format-attribute -Wredundant-decls -Werror=implicit -Werror=nonnull -Werror=init-self -Werror=main -Werror=missing-braces -Werror=sequence-point -Werror=return-type -Werror=trigraphs -Werror=array-bounds -Werror=write-strings -Werror=address -Werr
or=int-to-pointer-cast -Werror=pointer-to-int-cast -march=native -O -fstack-protector-strong -fno-plt -D_FORTIFY_SOURCE=2 -fPIC -D_DEFAULT_SOURCE -D_BSD_SOURCE -DHAS_FCHOWN -DHAS_STICKY_DIR_BIT -MD -MQ 'glamor/27c065b@@glamor@sta/glamor.c.o' -MF 'glamor/27c065b@@glamor@st
a/glamor.c.o.d' -o 'glamor/27c065b@@glamor@sta/glamor.c.o' -c ../xserver/glamor/glamor.c
In file included from ../xserver/glamor/glamor.c:37:
In file included from ../xserver/glamor/glamor_priv.h:43:
In file included from /usr/include/epoxy/egl.h:46:
In file included from /usr/include/epoxy/egl_generated.h:11:
In file included from /usr/include/EGL/eglplatform.h:128:
/usr/include/X11/Xlib.h:222:2: error: typedef redefinition with different types ('struct _XGC *' vs 'struct _GC')
*GC;
 ^
../xserver/include/gcstruct.h:282:3: note: previous definition is here
} GC;
  ^
1 error generated.
[338/805] Compiling C object 'Xext/02e353f@@libxserver_xext_vidmode@sta/vidmode.c.o'.
ninja: build stopped: subcommand failed.

tested:
mesa-19.2.1 + patches by Eric Engestrom
libglvnd-git-1.2.0.r4.g6fc91b9-1
xorg-server-git-1.20.0.r473.g5315f988-1