picocom: fix compilation with musl (#1383)

Only use termio.h with glibc or uclibc, for musl include sys/ioctl.h and
termios.h instead.

Signed-off-by: Jo-Philipp Wich <jow@openwrt.org>

utils/picocom/patches/100-musl-compat.patch

@@ -0,0 +1,17 @@
+Index: picocom-1.7/term.c
+===================================================================
+--- picocom-1.7.orig/term.c
++++ picocom-1.7/term.c
+@@ -33,10 +33,11 @@
+ #include <string.h>
+ #include <errno.h>
+ #include <unistd.h>
+-#ifdef __linux__
++#if defined(__linux__) && (defined(__GLIBC__) || defined(__UCLIBC__))
+ #include <termio.h>
+ #else
+ #include <termios.h>
++#include <sys/ioctl.h>
+ #endif /* of __linux__ */
+ 
+ #include "term.h"