[CMake] Simplify search for X11 components

Inspired by this forum post:
https://root-forum.cern.ch/t/install-root-in-my-directory-in-a-share-server/60150/2

cmake/modules/SearchInstalledSoftware.cmake

@@ -347,39 +347,17 @@ if(x11)
   if(X11_X11_INCLUDE_PATH)
     set(X11_FIND_QUIETLY 1)
   endif()
-  find_package(X11 REQUIRED)
-  if(X11_FOUND)
-    list(REMOVE_DUPLICATES X11_INCLUDE_DIR)
-    if(NOT X11_FIND_QUIETLY)
-      message(STATUS "X11_INCLUDE_DIR: ${X11_INCLUDE_DIR}")
-      message(STATUS "X11_LIBRARIES: ${X11_LIBRARIES}")
-    endif()
-  else()
-    message(FATAL_ERROR "libX11 and X11 headers must be installed.")
-  endif()
-  if(X11_Xpm_FOUND)
-    if(NOT X11_FIND_QUIETLY)
-      message(STATUS "X11_Xpm_INCLUDE_PATH: ${X11_Xpm_INCLUDE_PATH}")
-      message(STATUS "X11_Xpm_LIB: ${X11_Xpm_LIB}")
-    endif()
-  else()
-    message(FATAL_ERROR "libXpm and Xpm headers must be installed.")
-  endif()
-  if(X11_Xft_FOUND)
-    if(NOT X11_FIND_QUIETLY)
-      message(STATUS "X11_Xft_INCLUDE_PATH: ${X11_Xft_INCLUDE_PATH}")
-      message(STATUS "X11_Xft_LIB: ${X11_Xft_LIB}")
-    endif()
-  else()
-    message(FATAL_ERROR "libXft and Xft headers must be installed.")
-  endif()
-  if(X11_Xext_FOUND)
-    if(NOT X11_FIND_QUIETLY)
-      message(STATUS "X11_Xext_INCLUDE_PATH: ${X11_Xext_INCLUDE_PATH}")
-      message(STATUS "X11_Xext_LIB: ${X11_Xext_LIB}")
-    endif()
-  else()
-    message(FATAL_ERROR "libXext and Xext headers must be installed.")
+  find_package(X11 REQUIRED COMPONENTS Xpm Xft Xext)
+  list(REMOVE_DUPLICATES X11_INCLUDE_DIR)
+  if(NOT X11_FIND_QUIETLY)
+    message(STATUS "X11_INCLUDE_DIR: ${X11_INCLUDE_DIR}")
+    message(STATUS "X11_LIBRARIES: ${X11_LIBRARIES}")
+    message(STATUS "X11_Xpm_INCLUDE_PATH: ${X11_Xpm_INCLUDE_PATH}")
+    message(STATUS "X11_Xpm_LIB: ${X11_Xpm_LIB}")
+    message(STATUS "X11_Xft_INCLUDE_PATH: ${X11_Xft_INCLUDE_PATH}")
+    message(STATUS "X11_Xft_LIB: ${X11_Xft_LIB}")
+    message(STATUS "X11_Xext_INCLUDE_PATH: ${X11_Xext_INCLUDE_PATH}")
+    message(STATUS "X11_Xext_LIB: ${X11_Xext_LIB}")
   endif()
 endif()