package/gcc: bump to gcc 10.2

package/gcc: bump to gcc 10.2

Remove upstream patch backported to gcc 10.2:
https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=e86ae54172bb982e3c9d5aa62d20be5b72fe0f24

"GCC 10.2 is a bug-fix release from the GCC 10 branch
containing important fixes for regressions and serious bugs in
GCC 10.1 with more than 94 bugs fixed since the previous release."

https://gcc.gnu.org/pipermail/gcc-announce/2020/000164.html

Signed-off-by: Romain Naour <romain.naour@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>