Fix host-m4 build in new systems

Signed-off-by: falkTX <falktx@falktx.com>

Author: falkTX

global-packages/buildroot-2023.11.3/m4/m4.hash

@@ -0,0 +1,4 @@
+# Locally calculated after checking pgp signature
+sha256  63aede5c6d33b6d9b13511cd0be2cac046f2e70fd0a07aa9573a04a82783af96  m4-1.4.19.tar.xz
+# License files, locally calculated
+sha256  3972dc9744f6499f0f9b2dbf76696f2ae7ad8af9b23dde66d6af86c9dfb36986  COPYING

global-packages/buildroot-2023.11.3/m4/m4.mk

@@ -0,0 +1,23 @@
+################################################################################
+#
+# m4
+#
+################################################################################
+
+M4_VERSION = 1.4.19
+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_11),y)
+HOST_M4_CONF_ENV = CFLAGS="$(HOST_CFLAGS) -std=gnu17"
+endif
+
+$(eval $(host-autotools-package))