[DISCO_F746NG] missing gcc_arm in targets.py, travis build and dsp

[ohagendorf]

• adding missing GCC_ARM to target in targets.py
• updating dsp cmsis lib to current v4.5 because of missing cortex m7 in existing version
• adding linker option for float support in printf/scanf to be able to run both dsp test

Please see test results in the commits.

[0xc0170]

Please dont mix feature-sets within one PR , the 1st and 3rd commits could be merged right away. I have to now check the big commit changing >250 files no related to those 2 commits :)

[0xc0170]

Can you please remove the 2nd commit and send it separately? Will be easier to review + test + integrate

[ohagendorf]

I combined the commits because they are not independent - without the second one the first/last would get a failure during travis build. I started with the first commit because of issue #1435

There seems to be a small bug in travis build - thats why the dsp problem wasn't seen before by anybody:

• DISCO_F746 was already in travis build with fat and dsp library and gcc_arm as compiler
• DISCO_F746 was already in targets.py but WITHOUT gcc_arm
• this target was never build during travis build:
  • after adding gcc_arm to DISCO_F746 config in targets.py I got a dsp library compile failure - the dsp library version didn't support Cortex M7

The second commit is the original ARM CMSIS dsp library code without any changes except math_helper.h. That file was not change through the commit. The only difference between mbed version and ARM version is an extern "C" { ... }

So when I resubmit 2 PRs, one with first and last commit and the other with the second commit both have to be included into the main branch at the same time. When not the travis build would fail.

Do you still want that I put this PR into two different?

[0xc0170]

Thanks for clarification, let's leave it for as it is.