QM/MM Build Broken
As reported on gmx-users, installing QM/MM support with ORCA silently fails. Installation proceeds without error, but the mdrun binary gives a fatal error (Ab-initio calculation only supported with Gamess, Gaussian or ORCA.) From config.h, I can see that GMX_QMMM_ORCA is never #defined, and it appears that the environment variable is never set. I have found that GMX_QMMM_ORCA is not listed in config.h.cmakein, which causes the problem. I will upload a patch to Gerrit to fix this issue, but it appears that the ORCA QM/MM interface still does not actually work, since the mdrun executable fails with a fatal error, but that's a separate issue.
Fixes to config.h.cmakein to set GMX_QMMM_ORCA.
Installing using ORCA for QM calculations would proceed without
any issue, but the mdrun executable was nonfunctional because
GMX_QMMM_ORCA was never #defined, so the code was not correctly