gnu.cfg: Improved configuration for memrchr().

cfg/gnu.cfg

@@ -1127,6 +1127,7 @@
     <arg nr="1" direction="in">
       <not-null/>
       <not-uninit/>
+      <minsize type="argvalue" arg="3"/>
     </arg>
     <arg nr="2" direction="in">
       <not-uninit/>

test/cfg/gnu.c

@@ -21,9 +21,17 @@
 #ifndef __CYGWIN__
 #include <sys/epoll.h>
 #endif
-
 #include <strings.h>
 
+void *bufferAccessOutOfBounds_memrchr(const void *s, int c, size_t n)
+{
+    char buf[42]={0};
+    (void)memrchr(buf,c,42);
+    // cppcheck-suppress bufferAccessOutOfBounds
+    (void)memrchr(buf,c,43);
+    return memrchr(s,c,n);
+}
+
 void knownConditionTrueFalse_ffsl(long i)
 {
     // ffs() returns the position of the first bit set, or 0 if no bits are set in i.