Port configure script to C99

Related to:

  <https://fedoraproject.org/wiki/Changes/PortingToModernC>
  <https://fedoraproject.org/wiki/Toolchain/PortingToModernC>

kmod-configure-c99.patch

@@ -0,0 +1,37 @@
+configure.ac: In _Noreturn check, include <stdlib.h> for exit
+
+Otherwise, an implicit functiona declaration is used, causing
+a C99 compatibility issue.
+
+Submitted upstream:
+
+<https://lore.kernel.org/linux-modules/877cyq6kh9.fsf@oldenburg.str.redhat.com/>
+
+diff --git a/configure b/configure
+index d053310a8b4a313a..ec1f12d02428f848 100755
+--- a/configure
++++ b/configure
+@@ -14021,7 +14021,8 @@ rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
+ printf %s "checking whether _Noreturn is supported... " >&6; }
+ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+ /* end confdefs.h.  */
+-_Noreturn int foo(void) { exit(0); }
++#include <stdlib.h>
++	_Noreturn int foo(void) { exit(0); }
+ _ACEOF
+ if ac_fn_c_try_compile "$LINENO"
+ then :
+diff --git a/configure.ac b/configure.ac
+index 6989e9360da23721..12e0518533201ccf 100644
+--- a/configure.ac
++++ b/configure.ac
+@@ -68,7 +68,8 @@ AC_COMPILE_IFELSE(
+ 
+ AC_MSG_CHECKING([whether _Noreturn is supported])
+ AC_COMPILE_IFELSE(
+-	[AC_LANG_SOURCE([[_Noreturn int foo(void) { exit(0); }]])],
++	[AC_LANG_SOURCE([[#include <stdlib.h>
++	_Noreturn int foo(void) { exit(0); }]])],
+         [AC_DEFINE([HAVE_NORETURN], [1], [Define if _Noreturn is available])
+ 	 AC_MSG_RESULT([yes])],
+ 	[AC_MSG_RESULT([no])])

kmod.spec

@@ -16,7 +16,7 @@
 
 Name:		kmod
 Version:	30
-Release:	2%{?dist}
+Release:	3%{?dist}
 Summary:	Linux kernel module management utilities
 
 License:	GPLv2+
@@ -24,6 +24,7 @@ URL:		https://git.kernel.org/pub/scm/utils/kernel/kmod/kmod.git
 Source0:	https://www.kernel.org/pub/linux/utils/kernel/kmod/%{name}-%{version}.tar.xz
 Source1:	weak-modules
 Source2:	depmod.conf.dist
+Patch0:		kmod-configure-c99.patch
 Exclusiveos:	Linux
 
 BuildRequires:  gcc
@@ -69,6 +70,8 @@ applications that wish to load or unload Linux kernel modules.
 
 %prep
 %autosetup -p1
+# Avoid rebuilding the autoconf scripts.
+touch -r aclocal.m4 configure*
 
 %build
 %configure \
@@ -147,6 +150,9 @@ install -m 0644 %{SOURCE2} $RPM_BUILD_ROOT%{_sysconfdir}/depmod.d/dist.conf
 %{_libdir}/libkmod.so
 
 %changelog
+* Sat Dec 17 2022 Florian Weimer <fweimer@redhat.com> - 30-3
+- Port configure script to C99
+
 * Thu Jul 21 2022 Fedora Release Engineering <releng@fedoraproject.org> - 30-2
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_37_Mass_Rebuild