Add compatibility inet_aton() function for MinGW build

Based on a patch from Nikos Mavrogiannopoulos.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

compat.c

@@ -190,3 +190,11 @@ void openconnect__unsetenv(const char *name)
 	putenv(buf);
 }
 #endif
+
+#ifndef HAVE_INET_ATON
+int openconnect__inet_aton(const char *cp, struct in_addr *addr)
+{
+  addr->s_addr = inet_addr(cp);
+  return (addr->s_addr == 0xffffffff) ? 0 : 1;
+}
+#endif

configure.ac

@@ -141,7 +141,13 @@ AS_COMPILER_FLAGS(WFLAGS,
 AC_SUBST(WFLAGS, [$WFLAGS])
 
 AC_CHECK_FUNC(socket, [], AC_CHECK_LIB(socket, socket, [], AC_ERROR(Cannot find socket() function)))
-AC_CHECK_FUNC(inet_aton, [], AC_CHECK_LIB(nsl, inet_aton, [], AC_ERROR(Cannot find inet_aton() function)))
+
+have_inet_aton=yes
+AC_CHECK_FUNC(inet_aton, [], AC_CHECK_LIB(nsl, inet_aton, [], have_inet_aton=no))
+if test "$have_inet_aton" = "yes"; then
+   AC_DEFINE(HAVE_INET_ATON, 1)
+fi
+
 AC_CHECK_FUNC(__android_log_vprint, [], AC_CHECK_LIB(log, __android_log_vprint, [], []))
 
 AC_CHECK_FUNCS(setenv unsetenv)

openconnect-internal.h

@@ -364,6 +364,11 @@ int openconnect__setenv(const char *name, const char *value, int overwrite);
 void openconnect__unsetenv(const char *name);
 #endif
 
+#ifndef HAVE_INET_ATON
+#define inet_aton openconnect__inet_aton
+int openconnect__inet_aton(const char *cp, struct in_addr *addr);
+#endif
+
 /* I always coded as if it worked like this. Now it does. */
 #define realloc_inplace(p, size) do {			\
 	void *__realloc_old = p;			\