In https://go.dev/cl/384695
(https://gcc.gnu.org/pipermail/gcc-patches/2022-February/590289.html)
I simplified the code that built lists of benchmarks, examples, and
fuzz tests, and managed to break it. This patch corrects the code to
once again make the benchmarks available, and to run the examples with
output and the fuzz targets.

Doing this revealed a test failure in internal/fuzz on 32-bit x86: a
signalling NaN is turned into a quiet NaN on the 387 floating-point
stack that GCC uses by default. This CL skips the test.

This fixes https://go.dev/issue/60826.

Bootstrapped and ran Go testsuite on x86_64-pc-linux-gnu.  Committed
to mainline.

Ian