Remove --disable-cc-silence.

The explicit compiler warning suppression controlled by this option is
universally desirable, so remove the ability to disable suppression.

This partially resolves #580.

include/jemalloc/internal/jemalloc_internal_defs.h.in

@@ -127,9 +127,6 @@
 /* Non-empty if the tls_model attribute is supported. */
 #undef JEMALLOC_TLS_MODEL
 
-/* JEMALLOC_CC_SILENCE enables code that silences unuseful compiler warnings. */
-#undef JEMALLOC_CC_SILENCE
-
 /* JEMALLOC_CODE_COVERAGE enables test code coverage analysis. */
 #undef JEMALLOC_CODE_COVERAGE
 

include/jemalloc/internal/jemalloc_internal_macros.h

@@ -10,11 +10,7 @@
 #  define inline _inline
 #endif
 
-#ifdef JEMALLOC_CC_SILENCE
-#  define UNUSED JEMALLOC_ATTR(unused)
-#else
-#  define UNUSED
-#endif
+#define UNUSED JEMALLOC_ATTR(unused)
 
 #define ZU(z)	((size_t)z)
 #define ZD(z)	((ssize_t)z)

include/jemalloc/internal/util.h

@@ -26,11 +26,7 @@
  * wherever the compiler fails to recognize that the variable is never used
  * uninitialized.
  */
-#ifdef JEMALLOC_CC_SILENCE
-#  define JEMALLOC_CC_SILENCE_INIT(v) = v
-#else
-#  define JEMALLOC_CC_SILENCE_INIT(v)
-#endif
+#define JEMALLOC_CC_SILENCE_INIT(v) = v
 
 #ifdef __GNUC__
 #  define likely(x)   __builtin_expect(!!(x), 1)