As usual while waiting for the next release - don't forget to check the nightly builds in the forum.
mingw32-g++.exe -Wall -DCURL_STATICLIB -g -std=c++11 -IC:\lib\curl-7.40.0\curl-7.40.0\include -I -c ...\http.cpp -o obj\Debug\http.oc:/program files/codeblocks/mingw/bin/../lib/gcc/mingw32/4.7.1/../../../libmingw32.a(main.o):main.c:(.text.startup+0xa7): undefined reference to `WinMain@16'