unit-at-a-time option causes incorrect line numbers in warnings

[David Edelsohn]

>>>>> Joern Rennecke writes:

Joern> When flag_unit_at_a_time was set for -O2, gcc.dg/noreturn-1.c
Joern> failed in the test for warnings in line 11, since the warning
Joern> was emitted at the end of the compilation, and with line number
Joern> 59 instead of 11:

Joern> Executing on host: /export/home/build/sh64-elf/gcc/xgcc -B/export/home/build/sh64-elf/gcc/ /export/home/build/srcw/gcc/testsuite/gcc.dg/noreturn-1.c   -O2 -Wmissing-noreturn -DSTACK_SIZE=16384 -S 

	I am seeing a similar noreturn-1 failure on AIX PowerPC.

David