Fix function declaration behavior.

This only affects styles that prevent bin packing. There, a break after
a template declaration also forced a line break after the function name.

Before:
template <class SomeType, class SomeOtherType>
SomeType
SomeFunction(SomeType Type, SomeOtherType OtherType) {}

After:
template <class SomeType, class SomeOtherType>
SomeType SomeFunction(SomeType Type, SomeOtherType OtherType) {}

This fixes llvm.org/PR16072.