patch from Uz that makes some illegal operations on pointers error out

test/val/cc65150311.c

@@ -0,0 +1,38 @@
+/*
+  !!DESCRIPTION!! function pointer bugs
+  !!ORIGIN!!      testsuite
+  !!LICENCE!!     Public Domain
+  !!AUTHOR!!      Greg
+*/
+
+/*
+  see: http://www.cc65.org/mailarchive/2015-03/11726.html
+  and: http://www.cc65.org/mailarchive/2015-03/11734.html
+*/
+
+static int func(void) {return 0;}
+static int (*p)(void);
+static int n;
+
+int main(void) {
+
+    p = func;
+    n = (p == &func);
+    n = (p == func);
+
+/* the following are not valid C and should go into seperate tests that MUST fail */
+/*
+    ++p;
+    n = (p > &func);
+    n = (p > func);
+    n = func - func;
+    n = func - &func;
+    n = &func - func;
+    n = &func - &func;
+    n = p - &func;
+    n = p - func;
+    n = &func - p;
+    n = func - p;
+*/
+    return 0;
+}