Re: fossil build failure on riscv64

["Barak A. Pearlmutter" <barak@pearlmutter.net>]

I recompiled fossil 1:2.24 on ricci (riscv64) and ... it exhibits the
same problem!
Whereas the fossil package, compiled from the very same sources, does not.
According to ldd, they are using the same shared libraries.

So something must have changed in the riscv64 environment or tool
chain, like GCC.

# FRESHLY COMPILED from 1:2.24-6 sources:

$ ./fossil version
This is fossil version 2.24 [8be0372c10] 2024-04-23 13:25:26 UTC

$ ./fossil test-th-eval "expr (1<<31)"
-0./,),(-*,(

# PACKAGE, 1:2.24-6

$ /usr/bin/fossil version
This is fossil version 2.24 [5fe7dddc6f] 2024-04-30 14:34:12 UTC

$ /usr/bin/fossil test-th-eval "expr (1<<31)"
-2147483648