kconfig: let 'shell' return enough output for deep path names

stable inclusion
from stable-v5.10.102
commit 30455322787aee4bb95dcaabdcfcfaab69a1a8f0
bugzilla: https://gitee.com/openeuler/kernel/issues/I567K6

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=30455322787aee4bb95dcaabdcfcfaab69a1a8f0



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[ Upstream commit 8a4c5b2a ]

The 'shell' built-in only returns the first 256 bytes of the command's
output. In some cases, 'shell' is used to return a path; by bumping up
the buffer size to 4096 this lets us capture up to PATH_MAX.

The specific case where I ran into this was due to commit 1e860048
("gcc-plugins: simplify GCC plugin-dev capability test"). After this
change, we now use `$(shell,$(CC) -print-file-name=plugin)` to return
a path; if the gcc path is particularly long, then the path ends up
truncated at the 256 byte mark, which makes the HAVE_GCC_PLUGINS
depends test always fail.

Signed-off-by: Brenda Streiff <brenda.streiff@ni.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Yu Liao <liaoyu15@huawei.com>
Reviewed-by: Wei Li <liwei391@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>