usemem: fix build on systems with old glibc's

Headers from old versions of glibc don't have MAP_HUGE_SHIFT, which
leads to this:

 usemem.c:60:32: error: 'MAP_HUGE_SHIFT' undeclared (first use in this function)
  #define MAP_HUGE_2MB    (21 << MAP_HUGE_SHIFT)

With newer glibc's, MAP_HUGE_SHIFT is pulled in thusly:

  usemem.c
   sys/mman.h
    bits/mman.h
     bits/mman-linux.h
      # define MAP_HUGE_SHIFT 26

As a workaround, define MAP_HUGE_SHIFT manually just as usemem does with
MAP_HUGE_2MB.  While we're at it, remove the unused definition of
MAP_HUGE_1GB.  Tested on arch, debian, and oracle linux with
  ./usemem -UO $((2**21)).

Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/usemem.c b/usemem.c
index 38cd90a..bd22d98 100644
--- a/usemem.c
+++ b/usemem.c
@@ -56,12 +56,12 @@
 
 #define MAX_POINTERS	32
 
+#ifndef MAP_HUGE_SHIFT
+#define MAP_HUGE_SHIFT  26
+#endif
 #ifndef MAP_HUGE_2MB
 #define MAP_HUGE_2MB    (21 << MAP_HUGE_SHIFT)
 #endif
-#ifndef MAP_HUGE_1GB
-#define MAP_HUGE_1GB    (30 << MAP_HUGE_SHIFT)
-#endif
 
 char *ourname;
 int pagesize;