[vmc] Remove vmc, deprecated since 6.18.

.../pyroot/cppyy/cppyy-backend/cling/create_src_directory.py

cmake/modules/FindGEANT4VMC.cmake

cmake/modules/RootBuildOptions.cmake

cmake/modules/RootConfiguration.cmake

etc/vmc/MakeExe

etc/vmc/MakeMacros

etc/vmc/MakeRules

etc/vmc/Makedepend

etc/vmc/Makefile.hpuxacc

etc/vmc/Makefile.linux

etc/vmc/Makefile.linuxia64ecc

etc/vmc/Makefile.linuxia64gcc

etc/vmc/Makefile.linuxicc

etc/vmc/Makefile.linuxx8664gcc

etc/vmc/Makefile.linuxx8664icc

etc/vmc/Makefile.macosx

etc/vmc/Makefile.macosx64

etc/vmc/Makefile.macosxicc

etc/vmc/Makefile.solarisCC5

montecarlo/CMakeLists.txt