[Bug bootstrap/122924] [13/14/15/16 Regression] make bootstrap2 does not build dlang's std since r12-5631

[kirill at korins dot ky via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122924

--- Comment #8 from Kirill A. Korinsky <kirill at korins dot ky> ---
./gcc/gdc haven't got any dependency to libstdc++, and starts. But it needs
libstdc++ to link resulted test program to binary.