mesa: stop trying new filenames if the filename existing is not the issue

Signed-off-by: Eric Engestrom <eric.engestrom@intel.com>
Reviewed-by: Kristian H. Kristensen <hoegsberg@google.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
10 jobs for !1161 with mesa-shader_test-race in 8 minutes and 41 seconds (queued for 1 second)
detached
Status Job ID Name Coverage
  Containers Build
passed #388819
debian

00:00:18

 
  Build+Test
passed #388821
meson-clang

00:08:22

passed #388825
meson-clover

00:05:28

passed #388824
meson-main

00:04:00

passed #388820
meson-swr-glvnd

00:02:41

passed #388826
meson-vulkan

00:00:44

passed #388828
scons-llvm

00:05:17

passed #388827
scons-nollvm

00:02:39

passed #388822
scons-swr

00:03:32

passed #388823
scons-win64

00:03:01