ExternalProject: Find VCS packages quietly

This keeps the VCS packages out from FeatureSummary output, unless
the INCLUDE_QUIET_PACKAGES is used.

Modules/ExternalProject.cmake

@@ -1352,7 +1352,7 @@ function(_ep_add_download_command name)
   if(cmd_set)
     set(work_dir ${download_dir})
   elseif(cvs_repository)
-    find_package(CVS)
+    find_package(CVS QUIET)
     if(NOT CVS_EXECUTABLE)
       message(FATAL_ERROR "error: could not find cvs for checkout of ${name}")
     endif()
@@ -1379,7 +1379,7 @@ function(_ep_add_download_command name)
     set(cmd ${CVS_EXECUTABLE} -d ${cvs_repository} -q co ${cvs_tag} -d ${src_name} ${cvs_module})
     list(APPEND depends ${stamp_dir}/${name}-cvsinfo.txt)
   elseif(svn_repository)
-    find_package(Subversion)
+    find_package(Subversion QUIET)
     if(NOT Subversion_SVN_EXECUTABLE)
       message(FATAL_ERROR "error: could not find svn for checkout of ${name}")
     endif()
@@ -1415,7 +1415,7 @@ function(_ep_add_download_command name)
       --non-interactive ${svn_trust_cert_args} ${svn_user_pw_args} ${src_name})
     list(APPEND depends ${stamp_dir}/${name}-svninfo.txt)
   elseif(git_repository)
-    find_package(Git)
+    find_package(Git QUIET)
     if(NOT GIT_EXECUTABLE)
       message(FATAL_ERROR "error: could not find git for clone of ${name}")
     endif()
@@ -1463,7 +1463,7 @@ function(_ep_add_download_command name)
     set(cmd ${CMAKE_COMMAND} -P ${tmp_dir}/${name}-gitclone.cmake)
     list(APPEND depends ${stamp_dir}/${name}-gitinfo.txt)
   elseif(hg_repository)
-    find_package(Hg)
+    find_package(Hg QUIET)
     if(NOT HG_EXECUTABLE)
       message(FATAL_ERROR "error: could not find hg for clone of ${name}")
     endif()