fix include of prctl.h on alpine linux x86

Author: daanx

src/prim/unix/prim.c

@@ -32,7 +32,7 @@ terms of the MIT license. A copy of the license can be found in the file
 #if defined(__linux__)
   #include <features.h>
   #include <sys/prctl.h>    // THP disable, PR_SET_VMA
-  #if !defined(PR_SET_VMA)
+  #if defined(__GLIBC__) && !defined(PR_SET_VMA)
   #include <linux/prctl.h>
   #endif
   #if defined(__GLIBC__)