LibCore: compile puff.c as a separate object

Author: https://github.com/jcs
Commit: 2aeae2aea9
Pull-request: https://github.com/SerenityOS/serenity/pull/914

Libraries/LibCore/puff.h

@@ -21,6 +21,10 @@
   Mark Adler    madler@alumni.caltech.edu
  */
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /*
  * See puff.c for purpose and usage.
  */
@@ -32,3 +36,7 @@ int puff(unsigned char* dest,    /* pointer to destination pointer */
     unsigned long* destlen,      /* amount of output space */
     const unsigned char* source, /* pointer to source data pointer */
     unsigned long* sourcelen);   /* amount of input available */
+
+#ifdef __cplusplus
+}
+#endif