build: bump libdrm requirement to newer version (2.4.83)

There are some features that are available only if the user's libdrm version is
not too old: format modifiers require at least libdrm 2.4.71, atomic API at
least 2.4.78 and blob formats at least 2.4.83.

Bump libdrm to 2.4.83 (the oldest version that support these features) in order
to be able to remove ifdef checks and simplify the code. Major distributions
already support libdrm 2.4.91, so it's safe to apply this commit.

Signed-off-by: Leandro Ribeiro <leandrohr@riseup.net>

meson.build

@@ -139,7 +139,7 @@ dep_libinput = dependency('libinput', version: '>= 0.8.0')
 dep_libevdev = dependency('libevdev')
 dep_libm = cc.find_library('m')
 dep_libdl = cc.find_library('dl')
-dep_libdrm = dependency('libdrm', version: '>= 2.4.68')
+dep_libdrm = dependency('libdrm', version: '>= 2.4.83')
 dep_libdrm_headers = dep_libdrm.partial_dependency(compile_args: true)
 dep_threads = dependency('threads')