include/errno.h: skip set_errno in interrupt context

set_errno() should not modify the interrupted task's errno.
Add a check using up_interrupt_context() and skip the assignment
when called from an interrupt handler.

Signed-off-by: Jerry Ma <shichunma@bestechnic.com>

Author: masc2008

include/errno.h

@@ -28,6 +28,7 @@
  ****************************************************************************/
 
 #include <nuttx/compiler.h>
+#include <nuttx/irq.h>
 
 /****************************************************************************
  * Pre-processor Definitions
@@ -44,7 +45,10 @@
 #define set_errno(e) \
   do \
     { \
-      errno = (int)(e); \
+      if (!up_interrupt_context()) \
+        { \
+          errno = (int)(e); \
+        } \
     } \
   while (0)
 #define get_errno() errno