config.mak.dev: fix typo when enabling -Wpedantic

config.mak.dev: fix typo when enabling -Wpedantic

In ebd2e4a13a (Makefile: restrict -Wpedantic and -Wno-pedantic-ms-format
better, 2021-09-28), we tightened our Makefile's behavior to only enable
-Wpedantic when compiling with either gcc5/clang4 or greater as older
compiler versions did not have support for -Wpedantic.

Commit ebd2e4a13a was looking for either "gcc5" or "clang4" to appear in
the COMPILER_FEATURES variable, combining the two "$(filter ...)"
searches with an "$(or ...)".

But ebd2e4a13a has a typo where instead of writing:

    ifneq ($(or ($filter ...),$(filter ...)),)

we wrote:

    ifneq (($or ($filter ...),$(filter ...)),)

Causing our Makefile (when invoked with DEVELOPER=1, and a sufficiently
recent compiler version) to barf:

    $ make DEVELOPER=1
    config.mak.dev:13: extraneous text after 'ifneq' directive
    [...]

Correctly combine the results of the two "$(filter ...)" operations by
using "$(or ...)", not "$or".

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>