Cherry-pick a7616f1. rdar://116030136

    Cleanup webpushd.plist install location
    https://bugs.webkit.org/show_bug.cgi?id=263127
    rdar://116030136

    Reviewed by Elliott Williams.

    Restore the SYSTEM_SECONDARY_CONTENT_PATH behavior lost in a previous patch.

    * Source/WebKit/Configurations/webpushd.xcconfig:

    Canonical link: https://commits.webkit.org/269331@main
Identifier: 267815.310@safari-7617.1.11.11-branch

Source/WebKit/Configurations/webpushd.xcconfig

@@ -67,7 +67,7 @@ LAUNCHD_PLIST_INSTALL_PATH_YES = /System/Library/LaunchDaemons
 LAUNCHD_PLIST_INSTALL_PATH_YES[sdk=macos*] = /Library/Apple/System/Library/LaunchAgents
 
 LAUNCHD_PLIST_INSTALL_PATH_NO = /System/Library/LaunchDaemons
-LAUNCHD_PLIST_INSTALL_PATH_NO[sdk=macosx*] = /System/Library/LaunchAgents
+LAUNCHD_PLIST_INSTALL_PATH_NO[sdk=macos*] = $(SYSTEM_SECONDARY_CONTENT_PATH)/System/Library/LaunchAgents
 
 LAUNCHD_PLIST_OUTPUT_FILE = $(LAUNCHD_PLIST_OUTPUT_FILE_INSTALL_$(WK_NOT_$(SKIP_INSTALL)))
 LAUNCHD_PLIST_OUTPUT_FILE_INSTALL_YES = $(DSTROOT)$(LAUNCHD_PLIST_INSTALL_PATH)/$(LAUNCHD_PLIST_FILE_NAME)