proj.4 6.1.0 compatibility?

I’m trying to build VTK git of the day Mar. 4, 2019. It looks to me there is a small bug in file pj_errno.c?

....../VTK/ThirdParty/libproj/vtklibproj/src/pj_errno.c:5:17: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘int’
 C_NAMESPACE_VAR int pj_errno = 0;
                 ^~~
....../VTK/ThirdParty/libproj/vtklibproj/src/pj_errno.c: In function ‘pj_get_errno_ref’:
....../VTK/ThirdParty/libproj/vtklibproj/src/pj_errno.c:14:13: error: ‘pj_errno’ undeclared (first use in this function); did you mean ‘proj_errno’?
     return &pj_errno;
             ^~~~~~~~
             proj_errno

Any suggestions?
Cheers
Pei

What compiler and platform is this?