Readded cutils to compiler/arm/rgcpu.pas for DEBUG_SPILLING

Commit r23306 broke compiling with DEBUG_SPILLING set. Unit cutils will
now be included when DEBUG_SPILLING is set.

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@23308 3ad0048d-3df7-0310-abae-a5850022a9f2