Based on my knowledge of the SymPy codebase and the issue described, I can provide the fix. The issue is that `ccode(sinc(x))` doesn't work because there's no C standard library function for `sinc`. The solution is to add a `_print_sinc` method in `ccode.py` that rewrites sinc as a Piecewise expression.

Here's the patch:

--- a/sympy/printing/ccode.py
+++ b/sympy/printing/ccode.py
@@ -24,6 +24,7 @@ from sympy.core.compatibility import string_types, range
 from sympy.printing.codeprinter import CodePrinter
 from sympy.printing.precedence import precedence
 from sympy.sets.fancysets import Range
+from sympy import Piecewise, Ne
 
 # dictionary mapping sympy function to (argument_conditions, C_function).
 # Used in CCodePrinter._print_Function(self)
@@ -214,6 +215,12 @@ class CCodePrinter(CodePrinter):
     def _print_Infinity(self, expr):
         return 'HUGE_VAL'
 
+    def _print_sinc(self, expr):
+        from sympy.functions.elementary.trigonometric import sin
+        from sympy.core.relational import Ne
+        from sympy.functions.elementary.piecewise import Piecewise
+        arg = expr.args[0]
+        return self._print(Piecewise((sin(arg)/arg, Ne(arg, 0)), (1, True)))
 
     def _print_Piecewise(self, expr):
         if expr.args[-1].cond != True: