scripts: override locale from environment when running recordmcount.pl

recordmcount.pl uses a set of regular expressions to parse the output of
objdump(1). However, if objdump(1) output is localized, it may not match
the regular expressions, thereby preventing recordmcount.pl from parsing
object files correctly.

In order to allow recordmcount.pl to function correctly regardless of the
current locale settings, set LANG=C when running objdump(1). LC_ALL is
already unset in the top-level Makefile, so it is not necessary to also
override that environment variable.

Signed-off-by: Daniel Dadap <ddadap@nvidia.com>
Reviewed-by: Robert Morell <rmorell@nvidia.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>