build-kernel: Upgrade GCC version to 4.9

The target toolchain GCC version has been upgraded to 4.9 for a while.
The 4.8 toolchains were dropped in ChangeId:
I9f1b24b1606ac11856bee796204bbf68cd3ef6be.

Change-Id: Id57a91d96e8a2ff3ed066ff82dc9912bdc0662f0
1 file changed
tree: f8a003da8171d17c61258420443b48f5df72f418
  1. arm/
  2. arm64/
  3. kernel-toolchain/
  4. mips/
  5. mips64/
  6. x86/
  7. x86_64/
  8. build-kernel.sh