[PATCH] lib/getrandom.c: fix build with uclibc < 1.0.35

[Fabrice Fontaine]

Fix the following build failure with uclibc < 1.0.35 which is raised
since the addition of getrandom module in
https://git.savannah.gnu.org/cgit/gnulib.git/commit/?id=682cc4e678aceff32dea2a84b6e5147bdf5a20a7:

In file included from ./sys/random.h:40,
                 from getrandom.c:22:
/home/fabrice/buildroot/output/host/x86_64-buildroot-linux-uclibc/sysroot/usr/include/sys/random.h:27:35:
 error: unknown type name 'size_t'
   27 | extern int getrandom(void *__buf, size_t count, unsigned int flags)
      |                                   ^~~~~~
/home/fabrice/buildroot/output/host/x86_64-buildroot-linux-uclibc/sysroot/usr/include/sys/random.h:8:1:
 note: 'size_t' is defined in header '<stddef.h>'; did you forget to '#include 
<stddef.h>'?
    7 | #include <features.h>
  +++ |+#include <stddef.h>
    8 |

This patch is a workaround for uclibc < 1.0.35, upstream uclibc has been
patched with
https://github.com/wbx-github/uclibc-ng/commit/00972c02c2b6e0a95d5def4a71bdfb188e091782

Fixes:
 - 
http://autobuild.buildroot.org/results/adecc3e5def140348dfff30961fe6514c9a8e7b5

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
---
 lib/getrandom.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/lib/getrandom.c b/lib/getrandom.c
index 41212fb32..0ad3f9648 100644
--- a/lib/getrandom.c
+++ b/lib/getrandom.c
@@ -19,6 +19,7 @@
 
 #include <config.h>
 
+#include <stddef.h>
 #include <sys/random.h>
 
 #include <errno.h>
-- 
2.30.2