cleanup and work around visibility bug in gcc 3 that affects x86_64

in gcc 3, the visibility attribute must be placed on both the
declaration and on the definition. if it's omitted from the
definition, the compiler fails to emit the ".hidden" directive in the
assembly, and the linker will either generate textrels (if supported,
such as on i386) or refuse to link (on targets where certain types of
textrels are forbidden or impossible without further assumptions about
memory layout, such as on x86_64).

this patch also unifies the decision about when to use visibility into
libc.h and makes the visibility in the utf-8 state machine tables
based on libc.h rather than a duplicate test.

src/internal/libc.c

@@ -7,5 +7,5 @@ struct __libc *__libc_loc()
 	return &__libc;
 }
 #else
-struct __libc __libc;
+struct __libc __libc ATTR_LIBC_VISIBILITY;
 #endif

src/internal/libc.h

@@ -19,16 +19,21 @@ struct __libc {
 };
 
 
-#if 100*__GNUC__+__GNUC_MINOR__ >= 303 || defined(__PCC__) || defined(__TINYC__)
-extern struct __libc __libc __attribute__((visibility("hidden")));
-#define libc __libc
+#if !defined(__PIC__) || 100*__GNUC__+__GNUC_MINOR__ >= 303 || defined(__PCC__) || defined(__TINYC__)
 
-#elif !defined(__PIC__)
-extern struct __libc __libc;
+#ifdef __PIC__
+#define ATTR_LIBC_VISIBILITY __attribute__((visibility("hidden"))) 
+#else
+#define ATTR_LIBC_VISIBILITY
+#endif
+
+extern struct __libc __libc ATTR_LIBC_VISIBILITY;
 #define libc __libc
 
 #else
+
 #define USE_LIBC_ACCESSOR
+#define ATTR_LIBC_VISIBILITY
 extern struct __libc *__libc_loc(void) __attribute__((const));
 #define libc (*__libc_loc())
 

src/multibyte/internal.c

@@ -23,7 +23,7 @@
              | ( R(0x80,0xc0) >> 12 ) \
              | x )
 
-const uint32_t bittab[] = {
+const uint32_t bittab[] ATTR_LIBC_VISIBILITY = {
 	              C(0x2),C(0x3),C(0x4),C(0x5),C(0x6),C(0x7),
 	C(0x8),C(0x9),C(0xa),C(0xb),C(0xc),C(0xd),C(0xe),C(0xf),
 	D(0x0),D(0x1),D(0x2),D(0x3),D(0x4),D(0x5),D(0x6),D(0x7),

src/multibyte/internal.h

@@ -6,11 +6,9 @@
 
 #define bittab __fsmu8
 
-#if 100*__GNUC__+__GNUC_MINOR__ >= 303 || defined(__PCC__) || defined(__TINYC__)
-extern const uint32_t bittab[] __attribute__((visibility("hidden")));
-#else
-extern const uint32_t bittab[];
-#endif
+#include "libc.h"
+
+extern const uint32_t bittab[] ATTR_LIBC_VISIBILITY;
 
 /* Upper 6 state bits are a negative integer offset to bound-check next byte */
 /*    equivalent to: ( (b-0x80) | (b+offset) ) & ~0x3f      */