C model library: avoid duplicate *scanf definitions

glibc headers define C99 variants via asm renaming. Library checks
(rightly) failed when using clang 14, reporting duplicate definitions.

Fixes: #7366

Author: tautschnig

src/ansi-c/library/stdio.c

@@ -824,6 +824,8 @@ void perror(const char *s)
 
 /* FUNCTION: fscanf */
 
+#if !defined(__USE_ISOC99) || !defined(__REDIRECT)
+
 #ifndef __CPROVER_STDIO_H_INCLUDED
 #include <stdio.h>
 #define __CPROVER_STDIO_H_INCLUDED
@@ -844,6 +846,8 @@ __CPROVER_HIDE:;
   return result;
 }
 
+#endif
+
 /* FUNCTION: __isoc99_fscanf */
 
 #ifndef __CPROVER_STDIO_H_INCLUDED
@@ -868,6 +872,8 @@ __CPROVER_HIDE:;
 
 /* FUNCTION: scanf */
 
+#if !defined(__USE_ISOC99) || !defined(__REDIRECT)
+
 #ifndef __CPROVER_STDIO_H_INCLUDED
 #include <stdio.h>
 #define __CPROVER_STDIO_H_INCLUDED
@@ -888,6 +894,8 @@ __CPROVER_HIDE:;
   return result;
 }
 
+#endif
+
 /* FUNCTION: __isoc99_scanf */
 
 #ifndef __CPROVER_STDIO_H_INCLUDED
@@ -912,6 +920,8 @@ __CPROVER_HIDE:;
 
 /* FUNCTION: sscanf */
 
+#if !defined(__USE_ISOC99) || !defined(__REDIRECT)
+
 #ifndef __CPROVER_STDIO_H_INCLUDED
 #include <stdio.h>
 #define __CPROVER_STDIO_H_INCLUDED
@@ -932,6 +942,8 @@ __CPROVER_HIDE:;
   return result;
 }
 
+#endif
+
 /* FUNCTION: __isoc99_sscanf */
 
 #ifndef __CPROVER_STDIO_H_INCLUDED
@@ -956,6 +968,8 @@ __CPROVER_HIDE:;
 
 /* FUNCTION: vfscanf */
 
+#if !defined(__USE_ISOC99) || !defined(__REDIRECT)
+
 #ifndef __CPROVER_STDIO_H_INCLUDED
 #include <stdio.h>
 #define __CPROVER_STDIO_H_INCLUDED
@@ -998,6 +1012,8 @@ int vfscanf(FILE *restrict stream, const char *restrict format, va_list arg)
   return result;
 }
 
+#endif
+
 /* FUNCTION: __isoc99_vfscanf */
 
 #ifndef __CPROVER_STDIO_H_INCLUDED
@@ -1098,6 +1114,8 @@ int __stdio_common_vfscanf(
 
 /* FUNCTION: vscanf */
 
+#if !defined(__USE_ISOC99) || !defined(__REDIRECT)
+
 #ifndef __CPROVER_STDIO_H_INCLUDED
 #include <stdio.h>
 #define __CPROVER_STDIO_H_INCLUDED
@@ -1114,6 +1132,8 @@ int vscanf(const char *restrict format, va_list arg)
   return vfscanf(stdin, format, arg);
 }
 
+#endif
+
 /* FUNCTION: __isoc99_vscanf */
 
 #ifndef __CPROVER_STDIO_H_INCLUDED
@@ -1134,6 +1154,8 @@ __CPROVER_HIDE:;
 
 /* FUNCTION: vsscanf */
 
+#if !defined(__USE_ISOC99) || !defined(__REDIRECT)
+
 #ifndef __CPROVER_STDIO_H_INCLUDED
 #include <stdio.h>
 #define __CPROVER_STDIO_H_INCLUDED
@@ -1162,6 +1184,8 @@ __CPROVER_HIDE:;
   return result;
 }
 
+#endif
+
 /* FUNCTION: __isoc99_vsscanf */
 
 #ifndef __CPROVER_STDIO_H_INCLUDED