scripted-diff: Rename PACKAGE_* variables to CLIENT_*

This change ensures consistent use of the `CLIENT_` namespace everywhere
in the repository.

-BEGIN VERIFY SCRIPT-

ren() { sed -i "s/\<$1\>/$2/g" $( git grep -l "$1" ./cmake ./src :\(exclude\)./src/secp256k1 ./test ) ; }

ren PACKAGE_NAME      CLIENT_NAME
ren PACKAGE_VERSION   CLIENT_VERSION_STRING
ren PACKAGE_URL       CLIENT_URL
ren PACKAGE_BUGREPORT CLIENT_BUGREPORT

-END VERIFY SCRIPT-

src/init/common.cpp

@@ -146,6 +146,6 @@ void LogPackageVersion()
 #else
     version_string += " (release build)";
 #endif
-    LogPrintf(PACKAGE_NAME " version %s\n", version_string);
+    LogPrintf(CLIENT_NAME " version %s\n", version_string);
 }
 } // namespace init