add O_EXEC open mode

the linux O_PATH mode provides the necessary semantics for both the
O_SEARCH and O_EXEC modes defined and required by POSIX 2008.

arch/arm/bits/fcntl.h

@@ -11,6 +11,7 @@
 #define O_NOFOLLOW  0100000
 #define O_CLOEXEC  02000000
 #define O_SEARCH  010000000
+#define O_EXEC    010000000
 
 #define O_ASYNC      020000
 #define O_DIRECT    0200000

arch/i386/bits/fcntl.h

@@ -11,6 +11,7 @@
 #define O_NOFOLLOW  0400000
 #define O_CLOEXEC  02000000
 #define O_SEARCH  010000000
+#define O_EXEC    010000000
 
 #define O_ASYNC      020000
 #define O_DIRECT     040000

arch/mips/bits/fcntl.h

@@ -16,6 +16,7 @@
 #define O_CLOEXEC  02000000
 #define O_PATH    010000000
 #define O_SEARCH  010000000
+#define O_EXEC    010000000
 
 #define O_NDELAY O_NONBLOCK
 

arch/x86_64/bits/fcntl.h

@@ -11,6 +11,7 @@
 #define O_NOFOLLOW  0400000
 #define O_CLOEXEC  02000000
 #define O_SEARCH  010000000
+#define O_EXEC    010000000
 
 #define O_ASYNC      020000
 #define O_DIRECT     040000