[PATCH weston] build: honour libinput header location

[Emil Velikov]

From: Jan Engelhardt <jengelh at inai.de>

Add the respective CFLAGS to the build, otherwise the build will error
out as seen below.

src/libinput-seat.c:30:22: fatal error: libinput.h: No such file or directory

[Emil Velikov: polish commit message]
Signed-off-by: Emil Velikov <emil.velikov at collabora.com>
---
Jan, don't be shy to send patches upstream. Devs. won't bite... most of
the time ;-)
---
 Makefile.am | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Makefile.am b/Makefile.am
index b5c29c04..8de40e51 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -43,7 +43,8 @@ AM_CPPFLAGS = 					\
 	-I$(top_builddir)/protocol		\
 	-DLIBWESTON_MODULEDIR='"$(libweston_moduledir)"' \
 	-DLIBEXECDIR='"$(libexecdir)"'		\
-	-DBINDIR='"$(bindir)"'
+	-DBINDIR='"$(bindir)"' \
+	$(LIBINPUT_BACKEND_CFLAGS)
 
 CLEANFILES = weston.ini				\
 	ivi-shell/weston.ini			\
-- 
2.16.0