ridiculous memory consumption in libstdc++ test suite

[Zack Weinberg]

My current libstdc++ test results (mainline):

                === libstdc++ tests ===

FAIL: 21_strings/ctor_copy_dtor.cc (execution test), static  
FAIL: 21_strings/ctor_copy_dtor.cc (execution test), shared  
FAIL: 21_strings/insert.cc (execution test), static  
FAIL: 21_strings/insert.cc (execution test), shared  
FAIL: 22_locale/ctor_copy_dtor.cc (execution test), static  
FAIL: 22_locale/ctor_copy_dtor.cc (execution test), shared  
FAIL: 27_io/ios_members.cc (execution test), static  

                === libstdc++ Summary ===

# of expected passes            403
# of unexpected failures        7
# of expected failures          16

All the 21_strings failures are because I had to shoot the test
process after it chewed up all the RAM on the machine and well into
swap.  SIZE column in ps was >512MB in all cases.  The machine has
256 megs of real RAM and a gigabyte of swap.

I have tried setting ulimits before running make check, but they are
ineffective.  I may be setting the wrong ones, or something may be
resetting them.

I shouldn't have to kill tests or set ulimits in order for the test
suite to be a well-behaved background job and not interfere with my
ability to r/e/a/d/ U/s/e/n/e/t/ get work done while it's running.

zw