Fix stack noinline

Certain function must never be automatically inlined by gcc because
they are stack heavy or called recursively.  This patch flags all
such functions I've found as 'noinline' to prevent gcc from making
the optimization.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>

lib/libzpool/include/sys/zfs_context.h

@@ -75,6 +75,12 @@ extern "C" {
 #include <sys/sysevent/dev.h>
 #include <sys/sunddi.h>
 
+/*
+ * Stack
+ */
+
+#define  noinline	__attribute__((noinline))
+
 /*
  * Debugging
  */