Hi,

Attached is a small patch that, in case of inline assembler code, 
indicates that the function stack usage is uncertain due to inline 
assembler.

The test suite are using "nop" as an assembler instruction on all 
targets, is this acceptable or is there a better way to test this?

Patch has been tested on gcc-arm-none-eabi-7-2018-q2-update for both 
arm-none-eabi and x86_64-linux-gnu and SVN head (r266454) for 
x86_64-linux-gnu.

Thanks,
Torbjörn, Samuel and Niklas