bug#72379: srfi-64: test-approximate does not handle exceptions

Hello,

I think I found a bug in (srfi srfi-64) module shipped with GNU Guile.

The specification says that:

> The test also fails if an exception is raised, assuming the implementation has
> a way to catch exceptions.

Guile has a way to catch exceptions.  However nevertheless the following does
not lead to 'fail, but an exception being raised:

    (use-modules (srfi srfi-64))
    (test-begin "x")
    (test-approximate 1 (throw 'foo) 1)

Leading to:

    Backtrace:
    In ice-9/boot-9.scm:
      1752:10  8 (with-exception-handler _ _ #:unwind? _ #:unwind-for-type _)
    In unknown file:
               7 (apply-smob/0 #<thunk 7fd834112300>)
    In ice-9/boot-9.scm:
        724:2  6 (call-with-prompt _ _ #<procedure default-prompt-handler (k proc)>)
    In ice-9/eval.scm:
        619:8  5 (_ #(#(#<directory (guile-user) 7fd834115c80>)))
    In ice-9/boot-9.scm:
       2836:4  4 (save-module-excursion _)
      4388:12  3 (_)
    In /home/wolf/src/guile-wolfsden/tests/srfi-64/test-approximate-throw.srfi64test:
          7:0  2 (_)
    In srfi/srfi-64/testing.scm:
       677:16  1 (_ _ #f)
    In unknown file:
               0 (real-part #f)

    ERROR: In procedure real-part:
    In procedure real-part: Wrong type argument in position 1: #f

Have a nice day
Tomas Volf