Build: Add a check against GNUARM 10-2020-q4-major

GNU Arm compiler version 10-2020-q4-major has an issue in CMSE support.
Add a check against this version in toolchain_GNUARM.cmake to prevent
users from using this version by mistake.

Change-Id: I2540a291546ca024fca646a6e81f5679627d0cab
Signed-off-by: David Hu <david.hu@arm.com>
1 file changed