pgsql: Remove extra single-quotes copied from Unix build.

Log Message:
-----------
Remove extra single-quotes copied from Unix build. Win32 doesn't strip
single quotes...

Modified Files:
--------------
pgsql/src/tools/msvc:
builddoc.bat (r1.3 -> r1.4)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/tools/msvc/builddoc.bat.diff?r1=1.3&r2=1.4)