gnu: perl-sdl: Fix build with gcc@14.

* gnu/packages/perl.scm (perl-sdl)[arguments]<#:phases>{gcc-14}:
New phase to set CFLAGS.

Fixes: guix/guix#4630
Change-Id: I8bc422b6867e0c49586797b57ef49df2881fcbba
Signed-off-by: Andreas Enge <andreas@enge.fr>

gnu/packages/perl.scm

@@ -14608,7 +14608,12 @@ such that being individual extensions would be wasteful.")
                    ;;   Can't use an undefined value as a subroutine reference
                    ;;   during global destruction.
                    (substitute* "t/core_events.t"
-                     (("^SDL::Events::set_event_filter") "#")))))))
+                     (("^SDL::Events::set_event_filter") "#"))))
+               (add-after 'unpack 'gcc-14
+                 (lambda _
+                   (substitute* "inc/My/Builder.pm"
+                     (("^our \\$config =.*")
+                      "our $config = { ccflags => \"-Wno-error=implicit-function-declaration\" };")))))))
     (native-inputs
      (list perl-alien-sdl
            perl-capture-tiny