Fix mmap infinite recurse in memory patcher

This commit fixes issue #6853 by removing
MacOS/Darwin-specific logic from intercept_mmap.
It also opportunistically converts tabs to spaces.

Signed-off-by: Harumi Kuno <harumi.kuno@hpe.com>

opal/mca/memory/patcher/configure.m4

@@ -47,13 +47,15 @@ AC_DEFUN([MCA_opal_memory_patcher_CONFIG],[
     esac
     AC_MSG_RESULT([$opal_memory_patcher_happy])
 
+    # syscall interface causes compiler warnings.
+    # Per the above logic, memory patcher no longer supports MacOS/Darwin,
+    # so we no longer support Darwin-specific logic for intercept_mmap.
+    # See issue #6853: mmap infinite recurse in opal/mca/memory/patcher
     AS_IF([test "$opal_memory_patcher_happy" == "yes"], [
         AC_CHECK_FUNCS([__curbrk])
-	AC_CHECK_HEADERS([linux/mman.h sys/syscall.h])
-	AC_CHECK_DECLS([__mmap], [], [], [#include <sys/mman.h>])
-	AC_CHECK_FUNCS([__mmap])
-	AC_CHECK_DECLS([__syscall], [], [], [#include <sys/syscall.h>])
-	AC_CHECK_FUNCS([__syscall])
+        AC_CHECK_HEADERS([linux/mman.h sys/syscall.h])
+        AC_CHECK_DECLS([__syscall], [], [], [#include <sys/syscall.h>])
+        AC_CHECK_FUNCS([__syscall])
         $1], [$2])
 
     AC_CONFIG_FILES([opal/mca/memory/patcher/Makefile])

opal/mca/memory/patcher/memory_patcher_component.c

@@ -125,12 +125,7 @@ static void *_intercept_mmap(void *start, size_t length, int prot, int flags, in
     }
 
     if (!original_mmap) {
-#ifdef HAVE___MMAP
-        /* the darwin syscall returns an int not a long so call the underlying __mmap function */
-        result = __mmap (start, length, prot, flags, fd, offset);
-#else
         result = (void*)(intptr_t) memory_patcher_syscall(SYS_mmap, start, length, prot, flags, fd, offset);
-#endif
     } else {
         result = original_mmap (start, length, prot, flags, fd, offset);
     }