to the path and set SYSROOT to the SDK directory. e.g. with Xcode 4.5.2:
export PATH=$PATH:/Applications/Xcode.app/Contents/Developer/usr/bin
- export SYSROOT=/Applications/Xcode.app/Contents/Developer/SDKs/MacOSX10.7.sdk
+ export SYSROOT=/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.7.sdk
make;
(Lion™/Xcode 4.5.2™ recommended)