win warn: add definitions in TGLParametric.cxx only when not defined
win warn: add definitions in TGLParametric.cxx only when not defined

Original warning:
 C:\build\workspace\root-pullrequests-build\root\graf3d\gl\src\TGLParametric.cxx(14): warning C4005: 'NOMINMAX': macro redefinition [C:\build\workspace\root-pullrequests-build\build\graf3d\gl\RGL.vcxproj]

karies/root,olifre/root,karies/root,karies/root,karies/root,root-mirror/root,karies/root,olifre/root,karies/root,olifre/root,olifre/root,root-mirror/root,karies/root,root-mirror/root,olifre/root,root-mirror/root,karies/root,karies/root,karies/root,olifre/root,root-mirror/root,root-mirror/root,root-mirror/root,root-mirror/root,root-mirror/root,root-mirror/root,olifre/root,olifre/root,karies/root,olifre/root,root-mirror/root,olifre/root,olifre/root