*: work around sysinfo.h versus linux/*.h problems

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

procps/free.c

@@ -22,6 +22,9 @@
 //usage:       "Total:       386144       257128       129016\n"
 
 #include "libbb.h"
+#ifdef __linux__
+# include <sys/sysinfo.h>
+#endif
 
 struct globals {
 	unsigned mem_unit;

procps/ps.c

@@ -62,6 +62,9 @@ enum { MAX_WIDTH = 2*1024 };
 
 #if ENABLE_DESKTOP
 
+#ifdef __linux__
+# include <sys/sysinfo.h>
+#endif
 #include <sys/times.h> /* for times() */
 #ifndef AT_CLKTCK
 # define AT_CLKTCK 17

procps/uptime.c

@@ -25,6 +25,10 @@
 //usage:       "  1:55pm  up  2:30, load average: 0.09, 0.04, 0.00\n"
 
 #include "libbb.h"
+#ifdef __linux__
+# include <sys/sysinfo.h>
+#endif
+
 
 #ifndef FSHIFT
 # define FSHIFT 16              /* nr of bits of precision */