science/massxpert: fix build with GCC-based architectures

Replace USE_GCC=any with USE_GCC=yes to fix build on GCC architectures.

Build failure log:
CMake Error in lib/CMakeLists.txt:

The compiler feature "cxx_decltype" is not known to CXX compiler

"GNU"

 version 4.2.1.

Approved by: tcberner (mentor)
Differential Revision: https://reviews.freebsd.org/D20067