Why not install asterisk-126.96.36.199 with 'yum' or the
package manager : "Add / Remove Software" ? ?
1) su , password
2) yum install asterisk*
... the star ( * ) takes care, that all 30 packages are installed.
You are trying to compile an older version.
If you really want to do that, the c++ compiler is needed :
# yum install gcc-c++
But it is not recommended to build it yourself, the yum method
will result in a much more consistent system.