graphics: fix portable KMSCube execution across distros

[Srikanth Muppandam (smuppand)]

Fix KMSCube regressions observed on Yocto and Debian.

Changes

• Keep count-capable KMSCube builds in the proven foreground execution path.
• Detect --count support from the installed binary.
• Support standard Debian KMSCube builds without --count using controlled timeout execution.
• Fix non-portable awk failure-marker parsing.
• Support multiple rendered-frame summary formats.
• Require EGL and OpenGL initialization evidence for continuous builds.
• Retain capability, execution, and failure-marker diagnostics.
• Document count-capable and continuous execution behavior.