meson: explicitly depend on libwayland for includes

On BSDs base compiler doesn't search packages by default, making it
easy for vendors to depend only on base system.

FAILED: wlsunset.p/main.c.o
cc -Iwlsunset.p -I. -I.. -Xclang -fcolor-diagnostics -pipe -D_FILE_OFFSET_BITS=64 -Wall -Winvalid-pch -Wextra -Wpedantic -Werror -std=c11 -g -Wundef -Wunused -Wlogical-op -Wmissing-include-dirs -Wold-style-definition -Wpointer-arith -Wstrict-prototypes -Wimplicit-fallthrough -Wmissing-prototypes -Wno-unknown-warning-option -Wno-unused-command-line-argument -Wvla -Wl,--exclude-libs=ALL -D_USE_MATH_DEFINES -D_XOPEN_SOURCE=700 -MD -MQ wlsunset.p/main.c.o -MF wlsunset.p/main.c.o.d -o wlsunset.p/main.c.o -c ../main.c
../main.c:14:10: fatal error: 'wayland-client-protocol.h' file not found
 #include <wayland-client-protocol.h>
          ^~~~~~~~~~~~~~~~~~~~~~~~~~~
1 error generated.

meson.build

@@ -50,7 +50,7 @@ rt = cc.find_library('rt')
 executable(
 	'wlsunset',
 	['main.c', 'color_math.c'],
-	dependencies: [protocols_dep, m, rt],
+	dependencies: [wl_client, protocols_dep, m, rt],
 	install: true,
 )