[Gmsh] Cmake configuration problem with gmsh 4.5.1

[walter steffe]

Hello,

 I tried to configure gmsh 4.5.1 using cmake on ubuntu 18.04.
 The configure step is OK with the default cmake options but it fails
 after appling the following changes: 
      ENABLE_BUILD_LIB = ON
      ENABLE_FLTK = OFF

 Then configure fails with following error message:
 
      fatal: not a git repository (or any parent up to mount point /
      Stopping at filesystem boundary (GIT_DISCOVERY_ACROSS_FILESYSTEM not set)

 Regards
 Walter Steffè