[libc] fix sysconf test for rv32

Author: SchrodingerZhu

libc/src/__support/OSUtil/linux/auxv.h

@@ -16,6 +16,7 @@
 
 #include <linux/auxvec.h> // For AT_ macros
 #include <linux/mman.h>   // For mmap flags
+#include <linux/param.h>  // For EXEC_PAGESIZE
 #include <linux/prctl.h>  // For prctl
 #include <sys/syscall.h>  // For syscall numbers
 
@@ -90,7 +91,7 @@ LIBC_INLINE void Vector::fallback_initialize_unsync() {
                                      PROT_READ | PROT_WRITE,
                                      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
   // We do not proceed if mmap fails.
-  if (mmap_ret <= 0)
+  if (mmap_ret <= 0 && mmap_ret > -EXEC_PAGESIZE)
     return;
 
   // Initialize the auxv array with AT_NULL entries.