[Bug target/91602] GCC fails to build for riscv in a combined tree due to misconfigured leb128 support

[wilson at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91602

--- Comment #11 from Jim Wilson <wilson at gcc dot gnu.org> ---
Since Marxin pinged this and got me thinking about this again, I realized that
there is a simpler fix based on Serge's second suggestion.  We can just delete
the gas version number from the uleb128 gas check in configure.ac.  This will
force a gas feature check for uleb128 only, which solves the RISC-V build
problem, and is a nice small change.  I'm testing a patch for that.