max_align_t from libgnu/stddef.h conflicts with gcc 5.3.1

[Peter Simons]

Hi,

I'm using the current "master" of gnulib at v0.1-744-gf0be2ae to build a
C project on Linux/x86_64. This works fine with older compilers, but gcc
5.3.1 cannot build my project because of the following error:

    gcc -DHAVE_CONFIG_H -I. -I..   -DDEBUG  -g -O2 -MT unistd.o -MD -MP -MF 
.deps/unistd.Tpo -c -o unistd.o unistd.c
    In file included from unistd.h:56:0,
                     from unistd.c:3:
    ./stddef.h:104:3: error: conflicting types for 'max_align_t'
     } max_align_t;
       ^
    In file included from ./stddef.h:55:0,
                     from unistd.h:56,
                     from unistd.c:3:
    /usr/lib64/gcc/x86_64-suse-linux/5/include/stddef.h:429:3: note: previous 
declaration of 'max_align_t' was here
     } max_align_t;
       ^
    Makefile:647: recipe for target 'unistd.o' failed

Apparently, the stddef.h file provided by gnulib defines that type
differently than gcc 5.x does? Is that a known issue? Or am I using
gnulib wrong somehow?

Best regards,
Peter