util: Don't use "\e"

util: Don't use "\e"

'\e' representing ESC (0x1b) is not C standard, it's an GNU extension.
https://gcc.gnu.org/onlinedocs/gcc/Character-Escapes.html#Character-Escapes

Since the code also compiles on Windows with Microsoft compiler, we
should use '\033' instead.

Note: I didn't try to build the whole wpa_supplicant on Windows, so I
don't know if it still builds (I have no Visual Studio 2005 for a quick
test). I just needed the string conversion routines for the P"" syntax
in both directions.

Signed-off-by: Bernhard Walle <bernhard@bwalle.de>