clang: error: initializer element is not a compile-time constant in mathfunc.c

When compiling gnumeric-1.12.44 on NetBSD-8.99.30/amd64 with clang 7.0.0, I see:

mathfunc.c:5036:43: error: initializer element is not a compile-time constant

Removing the static from the definition of sqrt_one_over_e fixes the warning for me, see attached patch patch-src_mathfunc.c.