who has some idea on this issue?

After LIBCURL="-lcurldll" ./configure CFLAGS="-O3"

checking gmp.h usability... yes
checking gmp.h presence... yes
checking for gmp.h... yes
./configure: line 5726: syntax error near unexpected token `,'
./configure: line 5726: `LIBCURL_CHECK_CONFIG(, 7.15.2, ,'

RHEL 6.5
-bash-4.1# uname -a
Linux 2.6.32-431.el6.x86_64 #1 SMP Sun Nov 10 22:19:54 EST 2013 x86_64 x86_64 x86_64 GNU/Linux

BTW,can 1gh provide a miner which compiled well on rhel 6.X ?