package/m4: bump to 1.4.20

The new version bundles an updated gnulib that includes support for
-std=c23 which is the default for gcc 15.

Signed-off-by: Vincent Fazio <vfazio@gmail.com>
Signed-off-by: Arnout Vandecappelle <arnout@rnout.be>
(cherry picked from commit d9aabc1af39fc478e5aeee446bd2d814a2dcbda5)
Signed-off-by: Thomas Perale <thomas.perale@mind.be>

package/m4/m4.hash

@@ -1,4 +1,4 @@
 # Locally calculated after checking pgp signature
-sha256  63aede5c6d33b6d9b13511cd0be2cac046f2e70fd0a07aa9573a04a82783af96  m4-1.4.19.tar.xz
+sha256  e236ea3a1ccf5f6c270b1c4bb60726f371fa49459a8eaaebc90b216b328daf2b  m4-1.4.20.tar.xz
 # License files, locally calculated
 sha256  3972dc9744f6499f0f9b2dbf76696f2ae7ad8af9b23dde66d6af86c9dfb36986  COPYING

package/m4/m4.mk

@@ -4,20 +4,10 @@
 #
 ################################################################################
 
-M4_VERSION = 1.4.19
+M4_VERSION = 1.4.20
 M4_SOURCE = m4-$(M4_VERSION).tar.xz
 M4_SITE = $(BR2_GNU_MIRROR)/m4
 M4_LICENSE = GPL-3.0+
 M4_LICENSE_FILES = COPYING
 
-# gcc-15 defaults to -std=gnu23 which is incorrectly detected and
-# generates build failures in the gnulib copy included in
-# m4-1.4.19. We workaround this by forcing the previous gcc default
-# standard, which is -std=gnu17 only when host gcc is >= 15. This
-# workaround can be removed when m4 will be updated to a version
-# including a fix for gcc-15.
-ifeq ($(BR2_HOST_GCC_AT_LEAST_15),y)
-HOST_M4_CONF_ENV = CFLAGS="$(HOST_CFLAGS) -std=gnu17"
-endif
-
 $(eval $(host-autotools-package))