bpo-35374: Avoid trailing space in hhc file name if found on PATH. (GH-10849)

(cherry picked from commit e61cc481e02b758c8d8289163102c236d0658a55)

Co-authored-by: chrullrich <chris@chrullrich.net>
diff --git a/Doc/make.bat b/Doc/make.bat
index 461c35c..e660495 100644
--- a/Doc/make.bat
+++ b/Doc/make.bat
@@ -41,7 +41,7 @@
 
 rem Search for HHC in likely places
 set HTMLHELP=
-where hhc /q && set HTMLHELP=hhc && goto :skiphhcsearch
+where hhc /q && set "HTMLHELP=hhc" && goto :skiphhcsearch
 where /R ..\externals hhc > "%TEMP%\hhc.loc" 2> nul && set /P HTMLHELP= < "%TEMP%\hhc.loc" & del "%TEMP%\hhc.loc"
 if not exist "%HTMLHELP%" where /R "%ProgramFiles(x86)%" hhc > "%TEMP%\hhc.loc" 2> nul && set /P HTMLHELP= < "%TEMP%\hhc.loc" & del "%TEMP%\hhc.loc"
 if not exist "%HTMLHELP%" where /R "%ProgramFiles%" hhc > "%TEMP%\hhc.loc" 2> nul && set /P HTMLHELP= < "%TEMP%\hhc.loc" & del "%TEMP%\hhc.loc"