Change mesa libraries built with -optional in build visit.
<lib name="icet"/>
<lib name="ispc"/>
<lib name="llvm"/>
- <lib name="mesagl"/>
<lib name="mfem"/>
<lib name="mili"/>
<lib name="moab"/>
<lib name="netcdf"/>
<lib name="openexr"/>
<lib name="openssl"/>
+ <lib name="osmesa"/>
<lib name="ospray"/>
<lib name="pidx"/>
<lib name="p7zip"/>
