gtest: Remove extraneous semicolon from definition of XORG_TESTCASE

This makes it possible to use XORG_TESTCASE() as a statement. Currently
all uses of XORG_TESTCASE() that end with a semicolon result in a "empty
statement" warning.
3 jobs for cleanups in 1 minute and 30 seconds
Status Job ID Name Coverage
  Prep
passed #6278215
container-prep

00:00:09

 
  Install Xserver
passed #6278216
xserver-build

00:00:57

 
  Build
passed #6278217
build

00:00:22