Tweak opt_set, opt_enable

buildroot/bin/opt_enable

 
 for opt in "$@" ; do
   # Logic for returning nonzero based on answer here: https://stackoverflow.com/a/15966279/104648
-  eval "${SED} -i '/^[[:blank:]]*\(\/\/\)*[[:blank:]]*\(#define \b${opt}\b\)/{s//\2/;h};\${x;/./{x;q0};x;q9}' Marlin/Configuration.h" ||
-  eval "${SED} -i '/^[[:blank:]]*\(\/\/\)*[[:blank:]]*\(#define \b${opt}\b\)/{s//\2/;h};\${x;/./{x;q0};x;q9}' Marlin/Configuration_adv.h" ||
+  eval "${SED} -i '/^\([[:blank:]]*\/\/\)*[[:blank:]]*\(#define \b${opt}\b\)/{s//\2/;h};\${x;/./{x;q0};x;q9}' Marlin/Configuration.h" ||
+  eval "${SED} -i '/^\([[:blank:]]*\/\/\)*[[:blank:]]*\(#define \b${opt}\b\)/{s//\2/;h};\${x;/./{x;q0};x;q9}' Marlin/Configuration_adv.h" ||
   (echo "ERROR: opt_enable Can't find ${opt}" >&2 && exit 9)
 done

buildroot/bin/opt_set

 ARGC=$#
 while [[ $# > 1 ]]; do
   # Logic for returning nonzero based on answer here: https://stackoverflow.com/a/15966279/104648
-  eval "${SED} -i '/^[[:blank:]]*\(\/\/\)*\([[:blank:]]*\)\(#define\s\+\b${1}\b\).*$/{s//\2\3 ${2}/;h};\${x;/./{x;q0};x;q9}' Marlin/Configuration.h" ||
-  eval "${SED} -i '/^[[:blank:]]*\(\/\/\)*\([[:blank:]]*\)\(#define\s\+\b${1}\b\).*$/{s//\2\3 ${2}/;h};\${x;/./{x;q0};x;q9}' Marlin/Configuration_adv.h" ||
+  eval "${SED} -i '/^\([[:blank:]]*\)\(\/\/\)*\([[:blank:]]*\)\(#define\s\+\b${1}\b\).*$/{s//\1\3\4 ${2}/;h};\${x;/./{x;q0};x;q9}' Marlin/Configuration.h" ||
+  eval "${SED} -i '/^\([[:blank:]]*\)\(\/\/\)*\([[:blank:]]*\)\(#define\s\+\b${1}\b\).*$/{s//\1\3\4 ${2}/;h};\${x;/./{x;q0};x;q9}' Marlin/Configuration_adv.h" ||
   eval "echo '#define ${1} ${2}' >>Marlin/Configuration.h" ||
   (echo "ERROR: opt_set Can't set or add ${1}" >&2 && exit 9)
   shift 2