Build easycwmp base on openwrtorg/sdk image there are no libcurl found

I got the LIBCURL not found when I try to build easycwmp module, how I can fix it ? and I was installed the libcurl it still not working.
The out put:

checking for LIBCURL... no
configure: error: Package requirements (libcurl) were not met:

Package 'libcurl', required by 'virtual:world', not found

Consider adjusting the PKG_CONFIG_PATH environment variable if you
installed software in a non-standard prefix.

Alternatively, you may set the environment variables LIBCURL_CFLAGS
and LIBCURL_LIBS to avoid the need to call pkg-config.
See the pkg-config man page for more details.
make[2]: *** [Makefile:110: /home/build/openwr