Correct a commit 2151ccc56c ("Always organize test artifacts in a
directory hierarchy") regression causing:
Running .../gdb/testsuite/gdb.arch/mips16-thunks.exp ...
gdb compile failed, Assembler messages:
Fatal error: can't create .../gdb/testsuite/gdb.arch/mips16-thunks-inmain.o: No such file or directory
gdb compile failed, Assembler messages:
Fatal error: can't create .../gdb/testsuite/gdb.arch/mips16-thunks-main.o: No such file or directory
gdb compile failed, mips-mti-linux-gnu-gcc: error: .../gdb/testsuite/gdb.arch/mips16-thunks-inmain.o: No such file or directory
mips-mti-linux-gnu-gcc: error: .../gdb/testsuite/gdb.arch/mips16-thunks-main.o: No such file or directory
UNSUPPORTED: gdb.arch/mips16-thunks.exp: No MIPS16 support in the toolchain.
by using `standard_output_file' to construct output file names
throughout.
gdb/testsuite/
* gdb.arch/mips16-thunks.exp: Use `standard_output_file'
throughout.
