rendermode-feedback: fix stack-use-after-scope
==6305==ERROR: AddressSanitizer: stack-use-after-scope on address 0x007fed55c400 at pc 0x007f9bfa2108 bp 0x007fed55c0e0 sp 0x007fed55c0f8
READ of size 8 at 0x007fed55c400 thread T0
#0 0x7f9bfa2104 in piglit_run_selected_subtests piglit/tests/util/piglit-util.c:782
#1 0x40235c in piglit_display piglit/tests/spec/gl-1.0/rendermode-feedback.c:189
#2 0x7f9c533fc4 in run_test piglit/tests/util/piglit-framework-gl/piglit_fbo_framework.c:52
#3 0x401c70 in main piglit/tests/spec/gl-1.0/rendermode-feedback.c:118
[192, 384) 'tests' (line 104) <== Memory access at offset 192 is inside this variable
Signed-off-by: Patrick Lerda <patrick9876@free.fr>