This update for gcc7 fixes the following issues:

Update to gcc-7-branch head (r270528).

- Disables switch jump-tables when retpolines are used. This restores
some lost performance for kernel builds with retpolines. (bsc#1131264,
jsc#SLE-6738)
- Fix ICE compiling tensorflow on aarch64. (bsc#1129389)
- Fix for aarch64 FMA steering pass use-after-free. (bsc#1128794)
- Fix for s390x FP load-and-test issue. (bsc#1124644)
- Improve build reproducability by disabling address-space randomization
during build.
- Adjust gnat manual entries in the info directory. (bsc#1114592)
- Includes fix to no longer try linking -lieee with -mieee-fp. (bsc#1084842)

This update was imported from the SUSE:SLE-15:Update update project.