Remove setting ICUCORE for macOS in System.Globalization.Native CMake…

… config

Follow-up to dotnet#39833.

We don't link against ICU on macOS but load it via `dlopen()` at runtime and compilation uses headers from homebrew.
That means `HAVE_SET_MAX_VARIABLE` and `HAVE_UDAT_STANDALONE_SHORTER_WEEKDAYS` will always be defined and we don't need the ICUCORE variable.

src/libraries/Native/Unix/System.Globalization.Native/CMakeLists.txt

@@ -23,11 +23,6 @@ if(CLR_CMAKE_TARGET_UNIX)
         endif()
 
         if(CLR_CMAKE_TARGET_OSX)
-            find_library(ICUCORE icucore)
-            if(ICUCORE STREQUAL ICUCORE-NOTFOUND)
-                message(FATAL_ERROR "Cannot find libicucore, skipping build for System.Globalization.Native. .NET globalization is not expected to function.")
-                return()
-            endif()
             add_definitions(-DOSX_ICU_LIBRARY_PATH=\"/usr/lib/libicucore.dylib\")
             add_definitions(-DU_DISABLE_RENAMING)
         else()

src/libraries/Native/Unix/System.Globalization.Native/configure.cmake

@@ -1,4 +1,4 @@
-if(CLR_CMAKE_TARGET_ANDROID)
+if(CLR_CMAKE_TARGET_ANDROID OR CLR_CMAKE_TARGET_OSX)
     set(HAVE_SET_MAX_VARIABLE 1)
     set(HAVE_UDAT_STANDALONE_SHORTER_WEEKDAYS 1)
 else()
@@ -13,11 +13,7 @@ else()
             int main(void) { enum UDateFormatSymbolType e = UDAT_STANDALONE_SHORTER_WEEKDAYS; }
         " HAVE_UDAT_STANDALONE_SHORTER_WEEKDAYS)
 
-        if(CLR_CMAKE_TARGET_OSX)
-            set(CMAKE_REQUIRED_LIBRARIES ${ICUCORE})
-        else()
-            set(CMAKE_REQUIRED_LIBRARIES ${ICUUC} ${ICUI18N})
-        endif()
+        set(CMAKE_REQUIRED_LIBRARIES ${ICUUC} ${ICUI18N})
 
         check_symbol_exists(
             ucol_setMaxVariable