编译环境：
ubuntu版本：ubuntu 14.04
交叉编译工具链：OpenWrt-Toolchain-ramips-mt7628_gcc-4.8-linaro_uClibc-0.9.33.2.Linux-i686
编译库：libosip2-3.5.0、libeXosip2-3.5.0
报错内容：
1、libosip2-3.5.0
checking for the pthreads library -lpthreads... no
checking whether pthreads work without any flags... no
checking whether pthreads work with -Kthread... no
checking whether pthreads work with -kthread... no
checking for the pthreads library -llthread... no
checking whether pthreads work with -pthread... no
checking whether pthreads work with -pthreads... no
checking whether pthreads work with -mthreads... no
checking for the pthreads library -lpthread... no
checking whether pthreads work with --thread-safe... no
checking whether pthreads work with -mt... no2、libeXosip2-3.5.0
libtool: link: mipsel-openwrt-linux-gcc -g -DOSIP_MT -DENABLE_DEBUG -g -DENABLE_TRACE -g -o .libs/sip_reg sip_reg.o ../src/.libs/libeXosip2.so -L/usr/local/lib /usr/local/lib/libosipparser2.so /usr/local/lib/libosip2.so -lresolv
/usr/local/lib/libosip2.so: undefined reference to `pthread_create'
/usr/local/lib/libosip2.so: undefined reference to `sem_destroy'
/usr/local/lib/libosip2.so: undefined reference to `sem_wait'
/usr/local/lib/libosip2.so: undefined reference to `sem_post'
/usr/local/lib/libosip2.so: undefined reference to `sem_init'
/usr/local/lib/libosip2.so: undefined reference to `sem_trywait'
/usr/local/lib/libosip2.so: undefined reference to `pthread_join'
collect2: error: ld returned 1 exit status解决方法：在执行./configure文件后加入参数 LDFLAGS='-ldl'
执行脚本：
1、libosip2-3.5.0
./configure --host=mipsel-openwrt-linux LDFLAGS='-ldl'
make clean
make
make install2、libeXosip2-3.5.0
./configure --host=mipsel-openwrt-linux PKG_CONFIG_PATH=/usr/local/lib/pkgconfig LDFLAGS='-ldl'
make clean
make
make install---------------------------------------------------------------------------------------------------------------------------------------------------------------
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解决过程：
首先，我执行./configure -h查看帮助信息，发现
--enable-pthread enable support for POSIX threads. (default=autodetect)所以在配置脚本中加入这个选项
./configure --host=mipsel-openwrt-linux --enable-pthread
make clean
make
make installlibosip2-3.5.0库可以成功配置、编译、安装，但是但是但是，这是错的
因为接下来就是要交叉编译 libeXosip2-3.5.0 这个库，而上面的库是这个库的依赖库，编译过程中会出现上面报错内容中libeXosip2-3.5.0 的错。
所以直接加 --enable-pthread 并不能解决问题，问题还是在于没有正确编译 libosip2-3.5.0 库，然后我对比没有使用工具链和使用工具链间的差异，发现交叉编译配置后生成的config.h文件中没有定义HAVE_PTHREAD宏，于是手动增加
#define HAVE_PTHREAD 1这一语句，再次编译安装发现仍然不能解决问题，再接着就是分析两种配置的配置信息，没有使用工具链的配置信息如下
checking for the pthreads library -lpthreads... no
checking whether pthreads work without any flags... no
checking whether pthreads work with -Kthread... no
checking whether pthreads work with -kthread... no
checking for the pthreads library -llthread... no
checking whether pthreads work with -pthread... yes
checking for joinable pthread attribute... PTHREAD_CREATE_JOINABLE
checking if more special flags are required for pthreads... no对比后可以得到前面是一致的，只有后面几行有差异，所以这次我把两次编译的config.log文件复制出来，在打印那几句不同调试信息的位置进行查找，最终发现了几行关键的调试信息
/opt/OpenWrt-Toolchain-ramips-mt7628_gcc-4.8-linaro_uClibc-0.9.33.2.Linux-i686/toolchain-mipsel_24kec+dsp_gcc-4.8-linaro_uClibc-0.9.33.2/bin/../lib/gcc/mipsel-openwrt-linux-uclibc/4.8.3/../../../../mipsel-openwrt-linux-uclibc/bin/ld: warning: libdl.so.0, needed by /opt/OpenWrt-Toolchain-ramips-mt7628_gcc-4.8-linaro_uClibc-0.9.33.2.Linux-i686/toolchain-mipsel_24kec+dsp_gcc-4.8-linaro_uClibc-0.9.33.2/bin/../lib/gcc/mipsel-openwrt-linux-uclibc/4.8.3/../../../../mipsel-openwrt-linux-uclibc/lib/libpthread.so.0, not found (try using -rpath or -rpath-link)
/opt/OpenWrt-Toolchain-ramips-mt7628_gcc-4.8-linaro_uClibc-0.9.33.2.Linux-i686/toolchain-mipsel_24kec+dsp_gcc-4.8-linaro_uClibc-0.9.33.2/bin/../lib/gcc/mipsel-openwrt-linux-uclibc/4.8.3/../../../../mipsel-openwrt-linux-uclibc/lib/libpthread.so.0: undefined reference to `dlclose'
/opt/OpenWrt-Toolchain-ramips-mt7628_gcc-4.8-linaro_uClibc-0.9.33.2.Linux-i686/toolchain-mipsel_24kec+dsp_gcc-4.8-linaro_uClibc-0.9.33.2/bin/../lib/gcc/mipsel-openwrt-linux-uclibc/4.8.3/../../../../mipsel-openwrt-linux-uclibc/lib/libpthread.so.0: undefined reference to `dlopen'
/opt/OpenWrt-Toolchain-ramips-mt7628_gcc-4.8-linaro_uClibc-0.9.33.2.Linux-i686/toolchain-mipsel_24kec+dsp_gcc-4.8-linaro_uClibc-0.9.33.2/bin/../lib/gcc/mipsel-openwrt-linux-uclibc/4.8.3/../../../../mipsel-openwrt-linux-uclibc/lib/libpthread.so.0: undefined reference to `dlsym'然后百度一搜，结果是缺少了LDFLAGS='-ldl' 选项，最后在两个库的配置编译脚本中都加上这个选项后，编译安装完美通过。