Remove sizeof() as a special-case default argument value.

sourcepawn/compiler/tests/fail-newdecls.txt

@@ -2,4 +2,4 @@
 (2) : error 141: natives, forwards, and public functions cannot return arrays
 (3) : error 143: new-style declarations should not have "new"
 (5) : error 121: cannot specify array dimensions on both type and name
-(9) : error 025: function heading differs from prototype
+(11) : error 025: function heading differs from prototype

sourcepawn/compiler/tests/fail-sizeof-default-arg.sp

@@ -0,0 +1,9 @@
+stock void crab(int[] eggs, int numEggs = sizeof(eggs))
+{
+}
+
+public main()
+{
+  int eggs[12];
+  crab(eggs);
+}

sourcepawn/compiler/tests/fail-sizeof-default-arg.txt

@@ -0,0 +1 @@
+(1) : error 163: indeterminate array size in "sizeof" expression (symbol "eggs")