utf: do not define decode() to be inline

Currently, decode() is prototyped in utf.h, its body is in utf.c and it
is called from util.c.

However, decode() is defined to be inline, which can not work since,
when compiling util.c, the body of decode() is out-of-scope for that
compilation unit.

Furthermore, decode() uses a utf8d, which is a static defined in utf.c .
So utf8d is not visible when compiling util.c either.

This means that the definition of decode() along with utf8d is basically
wrong, and is now failing with gcc-5.x, with warnings like so:

    libtool: compile:  /home/ymorin/dev/buildroot/O/host/usr/bin/arm-linux-gcc -DHAVE_CONFIG_H -I. -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Wall -Wmissing-prototypes -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -c utf.c  -fPIC -DPIC -o .libs/libwebsock_la-utf.o
    utf.c:36:12: warning: ‘utf8d’ is static but used in inline function ‘decode’ which is not static
       *state = utf8d[256 + *state*16 + type];
                ^
    utf.c:30:19: warning: ‘utf8d’ is static but used in inline function ‘decode’ which is not static
       uint32_t type = utf8d[byte];
                       ^
    libtool: compile:  /home/ymorin/dev/buildroot/O/host/usr/bin/arm-linux-gcc -DHAVE_CONFIG_H -I. -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Wall -Wmissing-prototypes -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -c util.c  -fPIC -DPIC -o .libs/libwebsock_la-util.o
    In file included from websock.h:73:0,
                     from util.c:20:
    utf.h:25:17: warning: inline function ‘decode’ declared but never defined
     uint32_t inline decode(uint32_t *state, uint32_t *codep, uint32_t byte);
                     ^

This results in decode() to be omitted from libwebsock.so, and thus link
failures when another program wants to link with -lwebsock.

The simplest solution is to not inline decode() at all.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>

---
Note: an alternative would be to move both decode() and utf8d into
decode.h nad ditch decode.c if decode really must be inline. This is
left as an execise for an interested party. But since upstream hasn't
seen a single commit in more than a year now... :-(

diff -durN a/src/utf.c b/src/utf.c
--- a/src/utf.c	2014-07-15 01:43:20.000000000 +0200
+++ b/src/utf.c	2015-08-22 22:29:38.667393786 +0200
@@ -24,7 +24,7 @@
   1,3,1,1,1,1,1,3,1,3,1,1,1,1,1,1,1,3,1,1,1,1,1,1,1,1,1,1,1,1,1,1, // s7..s8
 };
 
-uint32_t inline
+uint32_t
 decode(uint32_t* state, uint32_t* codep, uint32_t byte)
 {
   uint32_t type = utf8d[byte];
diff -durN a/src/utf.h b/src/utf.h
--- a/src/utf.h	2014-07-15 01:43:20.000000000 +0200
+++ b/src/utf.h	2015-08-22 22:29:10.439227396 +0200
@@ -22,7 +22,7 @@
 
 #include <stdint.h>
 
-uint32_t inline decode(uint32_t *state, uint32_t *codep, uint32_t byte);
+uint32_t decode(uint32_t *state, uint32_t *codep, uint32_t byte);
 
 
 #endif /* UTF_H_ */