Move CPP_PROLOGUE and CPP_EPILOGUE to the .cpp

This lets us avoid having to specify them in every C file.

include/jemalloc/internal/atomic.h

@@ -3,8 +3,6 @@
 
 #define ATOMIC_INLINE static inline
 
-CPP_PROLOGUE
-
 #if defined(JEMALLOC_GCC_ATOMIC_ATOMICS)
 #  include "jemalloc/internal/atomic_gcc_atomic.h"
 #elif defined(JEMALLOC_GCC_SYNC_ATOMICS)
@@ -76,6 +74,4 @@ JEMALLOC_GENERATE_INT_ATOMICS(uint64_t, u64, 3)
 
 #undef ATOMIC_INLINE
 
-CPP_EPILOGUE
-
 #endif /* JEMALLOC_INTERNAL_ATOMIC_H */

include/jemalloc/internal/jemalloc_internal_includes.h

@@ -36,8 +36,6 @@
  * global jemalloc definitions, however.
  */
 
-CPP_PROLOGUE
-
 /******************************************************************************/
 /* HERMETIC HEADERS */
 /******************************************************************************/
@@ -149,6 +147,4 @@ CPP_PROLOGUE
 #include "jemalloc/internal/jemalloc_internal_inlines_c.h"
 #include "jemalloc/internal/prof_inlines_b.h"
 
-CPP_EPILOGUE
-
 #endif /* JEMALLOC_INTERNAL_INCLUDES_H */

include/jemalloc/internal/jemalloc_preamble.h.in

@@ -1,16 +1,6 @@
 #ifndef JEMALLOC_PREAMBLE_H
 #define JEMALLOC_PREAMBLE_H
 
-#ifdef __cplusplus
-#  define CPP_PROLOGUE extern "C" {
-#  define CPP_EPILOGUE }
-#else
-#  define CPP_PROLOGUE
-#  define CPP_EPILOGUE
-#endif
-
-CPP_PROLOGUE
-
 #include "jemalloc_internal_defs.h"
 #include "jemalloc/internal/jemalloc_internal_decls.h"
 
@@ -182,6 +172,4 @@ static const bool have_percpu_arena =
 #endif
     ;
 
-CPP_EPILOGUE
-
 #endif /* JEMALLOC_PREAMBLE_H */

include/jemalloc/internal/malloc_io.h

@@ -40,7 +40,6 @@
  */
 #define MALLOC_PRINTF_BUFSIZE	4096
 
-
 int buferror(int err, char *buf, size_t buflen);
 uintmax_t malloc_strtoumax(const char *restrict nptr, char **restrict endptr,
     int base);

src/jemalloc_cpp.cpp

@@ -2,9 +2,17 @@
 #include <new>
 
 #define JEMALLOC_CPP_CPP_
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 #include "jemalloc/internal/jemalloc_preamble.h"
 #include "jemalloc/internal/jemalloc_internal_includes.h"
 
+#ifdef __cplusplus
+}
+#endif
+
 // All operators in this file are exported.
 
 // Possibly alias hidden versions of malloc and sdallocx to avoid an extra plt