SystemInformation: Fix clang -Wtautological-pointer-compare warning

warning: comparison of array 'unameInfo.release' not equal to a null
         pointer is always true [-Wtautological-pointer-compare]
  if( unameInfo.release!=0 && strlen(unameInfo.release)>=3 )
      ~~~~~~~~~~^~~~~~~  ~

Indeed an array declared as 'char foo[x]' can never be NULL.
Removed check against null.

Change-Id: I0352ad50049d926e78b9ecc796493e898b1bfdb7