meson: Clean up finding ICU-UC on Visual Studio

Nowadays Meson has much better CMake support which we can use to find
dependencies on Visual Studio builds (and Visual Studio 2017 and later provides
CMake as an optional install item), so we can use it to help us find ICU-UC
on Visual Studio builds, since CMake has built-in support for finding it by
the components we need for some time.

meson.build

@@ -93,28 +93,15 @@ gobject_dep = dependency('gobject-2.0', required: get_option('gobject'))
 graphite2_dep = dependency('graphite2', required: get_option('graphite2'))
 graphite_dep = dependency('graphite2', required: get_option('graphite'))
 
-icu_dep = null_dep
-if not get_option('icu').disabled()
-  icu_dep = dependency('icu-uc', required: false)
-
-  if (not icu_dep.found() and
-      cpp.get_id() == 'msvc' and
-      cpp.has_header('unicode/uchar.h') and
-      cpp.has_header('unicode/unorm2.h') and
-      cpp.has_header('unicode/ustring.h') and
-      cpp.has_header('unicode/utf16.h') and
-      cpp.has_header('unicode/uversion.h') and
-      cpp.has_header('unicode/uscript.h'))
-    if get_option('buildtype') == 'debug'
-      icu_dep = cpp.find_library('icuucd', required: false)
-    else
-      icu_dep = cpp.find_library('icuuc', required: false)
-    endif
-  endif
-
-  if not icu_dep.found()
-    icu_dep = dependency('icu-uc', required: get_option('icu'))
-  endif
+if cpp.get_argument_syntax() == 'msvc'
+  icu_dep = dependency('ICU',
+                       required: get_option('icu'),
+                       components: 'uc',
+                       method: 'cmake')
+else
+  icu_dep = dependency('icu-uc',
+                       required: get_option('icu'),
+                       method: 'pkg-config')
 endif
 
 if icu_dep.found() and icu_dep.type_name() == 'pkgconfig'