selftests/mm: guard defines from shm

thuge-gen.c defines SHM_HUGE_* macros that are provided by the uapi since
4.14.  These macros get redefined when compiling with Android's bionic
because its sys/shm.h will import the uapi definitions.

However if linux/shm.h is included, with glibc, sys/shm.h will clash on
some struct definitions:

  /usr/include/linux/shm.h:26:8: error: redefinition of ‘struct shmid_ds’
     26 | struct shmid_ds {
        |        ^~~~~~~~
  In file included from /usr/include/x86_64-linux-gnu/bits/shm.h:45,
                   from /usr/include/x86_64-linux-gnu/sys/shm.h:30:
  /usr/include/x86_64-linux-gnu/bits/types/struct_shmid_ds.h:24:8: note: originally defined here
     24 | struct shmid_ds
        |        ^~~~~~~~

For now, guard the SHM_HUGE_* defines with ifndef to prevent redefinition
warnings on Android bionic.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Edward Liaw <[email protected]>
Reviewed-by: Carlos Llamas <[email protected]>
Reviewed-by: Muhammad Usama Anjum <[email protected]>
Cc: Bill Wendling <[email protected]>
Cc: Carlos Llamas <[email protected]>
Cc: Justin Stitt <[email protected]>
Cc: Nathan Chancellor <[email protected]>
Cc: Nick Desaulniers <[email protected]>
Cc: Shuah Khan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: edliaw

tools/testing/selftests/mm/thuge-gen.c

@@ -34,10 +34,18 @@
 #endif
 
 #define SHM_HUGETLB     04000   /* segment will use huge TLB pages */
+#ifndef SHM_HUGE_SHIFT
 #define SHM_HUGE_SHIFT  26
+#endif
+#ifndef SHM_HUGE_MASK
 #define SHM_HUGE_MASK   0x3f
+#endif
+#ifndef SHM_HUGE_2MB
 #define SHM_HUGE_2MB    (21 << SHM_HUGE_SHIFT)
+#endif
+#ifndef SHM_HUGE_1GB
 #define SHM_HUGE_1GB    (30 << SHM_HUGE_SHIFT)
+#endif
 
 #define NUM_PAGESIZES   5
 #define NUM_PAGES 4