add required glibc-static package required to manually build

Documentation/building.md

@@ -25,7 +25,7 @@ Then you should be able to set the ARCH as above
     * On Ubuntu, run `sudo apt-get install linux-libc-dev golang gcc`. 
       If the golang version installed is not 1.7 or higher. Download the newest golang and install manully.
       To build the flannel.exe on windows, mingw-w64 is also needed. Run command `sudo apt-get install mingw-w64`
-    * On Fedora/Redhat, run `sudo yum install kernel-headers golang gcc`.
+    * On Fedora/Redhat, run `sudo yum install kernel-headers golang gcc glibc-static`.
 2. Git clone the flannel repo. It MUST be placed in your GOPATH under `github.com/coreos/flannel`: `cd $GOPATH/src; git clone https://github.com/coreos/flannel.git`
 3. Run the build script, ensuring that `CGO_ENABLED=1`: `cd flannel; CGO_ENABLED=1 make dist/flanneld` for linux usage.
    Run the build script, ensuring that `CGO_ENABLED=1`: `cd flannel; CGO_ENABLED=1 make dist/flanneld.exe` for windows usage.