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