[gdb/testsuite] Use build_executable in gdb.tui/tui-missing-src.exp
While looking at test-case gdb.tui/tui-missing-src.exp I noticed that
gdb_compile is used to compile multiple sources:
...
if { [gdb_compile "${srcfiles}" "${binfile}" \
executable {debug additional_flags=-O0}] != "" } {
...
meaning there are no separate compile and link steps, as is required for
fission [1].
Fix this by using build_executable instead.
Tested on aarch64-linux.
[1] https://gcc.gnu.org/wiki/DebugFission
1 file changed
