gcc is unable to create an executable file.

错误如下：

gcc is unable to create an executable file.
If gcc is a cross-compiler, use the --enable-cross-compile option.
Only do this if you know what cross compiling means.
C compiler test failed.

网上也没找到资料。后来发现错误是extra-cflags/extra-ldflags写错了。正确写法是：

./configure \
          --prefix=${DEST_LIB_DIR} \
    --extra-cflags=-I${DEST_LIB_DIR}/include \
    --extra-cflags=-I${DEST_LIB_DIR}/include/freetype2 \
   --extra-ldflags=-L${DEST_LIB_DIR}/lib \