编译gnutls找不到nettle3.1的问题

编译环境：win10 64位，　cygwin64位。

１，安装cygwin时没有装pkg-config.exe，通过重新运行setup-x86_64.exe，在选择包时搜索找到所在包安装成功；

２，confingure时仍提示问题存在。看LOGconfigure:9764: checking for NETTLE
configure:9772: $PKG_CONFIG --exists --print-errors "nettle >= 3.1"
Package nettle was not found in the pkg-config search path.
Perhaps you should add the directory containing `nettle.pc'
to the PKG_CONFIG_PATH environment variable

提示需要设置一个PKG_CONFIG_PATH环境变量。

执行　export PKG_CONFIG_PATH=/usr/local/lib/pkgconfig　后问题解决