Merge pull request #4 from jcoyne/patch-1

Fix compilation with musl libc

src/os/linux/linux_sigar.c

@@ -50,6 +50,10 @@
 #define PROC_PARTITIONS PROC_FS_ROOT "partitions"
 #define PROC_DISKSTATS  PROC_FS_ROOT "diskstats"
 
+#ifndef HZ
+#define HZ 100
+#endif
+
 /*
  * /proc/self/stat fields:
  * 1 - pid

src/os/linux/sigar_os.h

@@ -70,7 +70,7 @@ struct sigar_t {
 };
 
 #define HAVE_STRERROR_R
-#ifndef __USE_XOPEN2K
+#if !defined(__USE_XOPEN2K) && defined(__GLIBC__)
 /* use gnu version of strerror_r */
 #define HAVE_STRERROR_R_GLIBC
 #endif