ldbl-128ibm-compat: Add local aliases for printf family symbols

When the compiler selects IEEE-128 long double ABI(-mabi=ieeelongdouble),
calls to printf, fprintf, sprintf and snprintf are redirected to the
__printfieee128, __fprintfieee128, __sprintfieee128 and __snprintfieee128
symbols respectively.  This causes "break printf" (and others) in
GDB to fail because the original symbol names do not exist as global
symbols in libc.so.6.

Fix this by adding local symbol aliases in the ieee128 compatibility
files so that the original symbol names are present in the symbol table
again.  This restores the expected GDB behavior ("break printf" works)
without requiring dynamic symbols or versioned compatibility symbols.

Suggested-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>

sysdeps/ieee754/ldbl-128ibm-compat/ieee128-fprintf.c

@@ -33,3 +33,4 @@ ___ieee128_fprintf (FILE *fp, const char *format, ...)
 }
 strong_alias (___ieee128_fprintf, __fprintfieee128)
 hidden_def (___ieee128_fprintf)
+asm (".local fprintf\n" ".set fprintf, __fprintfieee128");

sysdeps/ieee754/ldbl-128ibm-compat/ieee128-printf.c

@@ -33,3 +33,4 @@ ___ieee128_printf (const char *format, ...)
   return done;
 }
 strong_alias (___ieee128_printf, __printfieee128)
+asm (".local printf\n" ".set printf, __printfieee128");

sysdeps/ieee754/ldbl-128ibm-compat/ieee128-snprintf.c

@@ -37,3 +37,4 @@ ldbl_hidden_def (___ieee128_snprintf, ___ieee128_snprintf)
 #ifdef SHARED
 strong_alias (___ieee128_snprintf, __GI____ieee128___snprintf)
 #endif
+asm (".local snprintf\n" ".set snprintf, __snprintfieee128");

sysdeps/ieee754/ldbl-128ibm-compat/ieee128-sprintf.c

@@ -34,3 +34,4 @@ ___ieee128_sprintf (char *s, const char *format, ...)
 }
 strong_alias (___ieee128_sprintf, __sprintfieee128)
 hidden_def (___ieee128_sprintf)
+asm (".local sprintf\n" ".set sprintf, __sprintfieee128");