build: Unbreak build on FreeBSD by adjusting dependencies (#5595)

* deps: add epoll-shim for some BSDs after 863c7b6072

ld: error: undefined symbol: timerfd_create
>>> referenced by EventLoopManager.cpp
>>>               src/Hyprland.p/managers_eventLoop_EventLoopManager.cpp.o:(CEventLoopManager::CEventLoopManager())

ld: error: undefined symbol: timerfd_settime
>>> referenced by EventLoopManager.cpp
>>>               src/Hyprland.p/managers_eventLoop_EventLoopManager.cpp.o:(CEventLoopManager::nudgeTimers())

See also
https://github.com/freebsd/freebsd-src/commit/af93fea71038
https://github.com/netbsd/src/commit/75f1bc6655cf

* deps: drop unused xcb-image after 45945a3e7d

$ pkg install <hyprland dependencies>
$ pkg install meson jq `pkg rquery %dn wlroots` hwdata
$ gmake all
[...]
-- Checking for modules 'xcb;xwayland;xcb-util;xcb-render;xcb-image;xcb-xfixes;xcb-icccm;xcb-composite;xcb-res;xcb-ewmh'
--   Package 'xcb-image' not found
CMake Error at /usr/local/share/cmake/Modules/FindPkgConfig.cmake:619 (message):
  The following required packages were not found:

   - xcb-image

Call Stack (most recent call first):
  /usr/local/share/cmake/Modules/FindPkgConfig.cmake:841 (_pkg_check_modules_internal)
  CMakeLists.txt:177 (pkg_check_modules)

See also
https://github.com/swaywm/wlroots/commit/ae7c3f3d1c56

meson.build

@@ -51,6 +51,7 @@ if not have_xwayland
 endif
 
 backtrace_dep = cpp_compiler.find_library('execinfo', required: false)
+epoll_dep = dependency('epoll-shim', required: false) # timerfd on BSDs
 systemd_dep = dependency('libsystemd', required: get_option('systemd'))
 
 if get_option('systemd').enabled()