Failure of test g++.dg/mangle.C on cygwin.

[Billinghurst, David (CRTS)]

The test  g++.dg/mangle1.C fails with 3.0 and 3.1 on cygwin, with

FAIL: g++.dg/mangle1.C scan-assembler _ZN1A1fEv:
FAIL: g++.dg/mangle1.C scan-assembler _ZN1AC2Ev:
FAIL: g++.dg/mangle1.C scan-assembler _ZN1BC2Ev:
FAIL: g++.dg/mangle1.C scan-assembler _ZN1CC1Ev:
FAIL: g++.dg/mangle1.C scan-assembler _ZTC1C0_1B:
FAIL: g++.dg/mangle1.C scan-assembler _ZTI1A:
FAIL: g++.dg/mangle1.C scan-assembler _ZTI1B:
FAIL: g++.dg/mangle1.C scan-assembler _ZTI1C:
FAIL: g++.dg/mangle1.C scan-assembler _ZTS1A:
FAIL: g++.dg/mangle1.C scan-assembler _ZTS1B:
FAIL: g++.dg/mangle1.C scan-assembler _ZTS1C:
FAIL: g++.dg/mangle1.C scan-assembler _ZTT1C:
FAIL: g++.dg/mangle1.C scan-assembler _ZTV1A:
FAIL: g++.dg/mangle1.C scan-assembler _ZTV1C:
FAIL: g++.dg/mangle1.C scan-assembler _ZTv0_n12_N1A1fEv:

The symbols in mangle1.s have two leading underscores, while the test
requires one leading underscore.  Which is correct?