gcc: Fix tm.h plugin header

On x86-64, tm.h (needed to build gcc plugins) tries to include
config/i386/linux64.h, which isn't installed. Fortunately it also
isn't used, so simply removing the include statement is an ok fix.

Sample failure see
https://git.ostc-eu.org/OSTC/OHOS/meta-ohos/-/jobs/43762



Signed-off-by: Bernhard Rosenkränzer <bernhard.rosenkraenzer.ext@huawei.com>