Fix matrix mangled name
Fix matrix mangled name

NxM matrices weren't mangled properly,
since only the nominal size was taken
into account, not the secondary size,
in the mangled name.

Change-Id: I94f4d8e1909cce085e8748bbe5355c5f17b0e7c2
Reviewed-on: https://swiftshader-review.googlesource.com/3271
Tested-by: Alexis Hétu <1c7141772178a7e80858c3db5052b328076f08f4@google.com>
Reviewed-by: Nicolas Capens <0612353e1fcebbfd4b302d9337447ca0cdfa9122@google.com>

bkaradzic/SwiftShader,google/swiftshader,google/swiftshader,bkaradzic/SwiftShader,google/swiftshader,bkaradzic/SwiftShader,bkaradzic/SwiftShader,bkaradzic/SwiftShader