node-gyp-bin: fix custom node-gyp env var quoting
node-gyp-bin: fix custom node-gyp env var quoting

npm sets node_config_node_gyp without quotes, so its usage should be
quoted. Indeed, it is a better practice to define environment variables
that contain paths without quotes and quote their usage.

PR-URL: https://github.com/npm/npm/pull/11158
Credit: da39a3ee5e6b4b0d3255bfef95601890afd80709@orangemocha
Reviewed-By: da39a3ee5e6b4b0d3255bfef95601890afd80709@othiym23

chadnickbok/npm,midniteio/npm,Volune/npm,yibn2008/npm,cchamberlain/npm-msys2,Volune/npm,yibn2008/npm,rsp/npm,cchamberlain/npm,DaveEmmerson/npm,evocateur/npm,DIREKTSPEED-LTD/npm,cchamberlain/npm,evanlucas/npm,misterbyrne/npm,yodeyer/npm,rsp/npm,DIREKTSPEED-LTD/npm,lxe/npm,xalopp/npm,kimshinelove/naver-npm,evocateur/npm,misterbyrne/npm,yodeyer/npm,misterbyrne/npm,cchamberlain/npm-msys2,TimeToogo/npm,DaveEmmerson/npm,lxe/npm,xalopp/npm,TimeToogo/npm,midniteio/npm,TimeToogo/npm,yodeyer/npm,evocateur/npm,evanlucas/npm,chadnickbok/npm,Volune/npm,evanlucas/npm,kimshinelove/naver-npm,lxe/npm,xalopp/npm,cchamberlain/npm,DaveEmmerson/npm,midniteio/npm,chadnickbok/npm,cchamberlain/npm-msys2,kimshinelove/naver-npm,DIREKTSPEED-LTD/npm,rsp/npm,yibn2008/npm