Rename gbt files to bitcoin since they'll have multiple bitcoin functions not just gbt

src/Makefile.am

@@ -5,5 +5,5 @@ libckpool_la_SOURCES = libckpool.c libckpool.h
 libckpool_la_LIBADD = @PTHREAD_LIBS@ @MATH_LIBS@ @RT_LIBS@ @JANSSON_LIBS@
 
 bin_PROGRAMS = ckpool
-ckpool_SOURCES = ckpool.c ckpool.h gbt.c gbt.h
+ckpool_SOURCES = ckpool.c ckpool.h bitcoin.c bitcoin.h
 ckpool_LDADD = libckpool.la

src/bitcoin.h

@@ -7,4 +7,9 @@
  * any later version.  See COPYING for more details.
  */
 
+#ifndef BITCOIN_H
+#define BITCOIN_H
+
 bool validate_address(connsock_t *cs, const char *address);
+
+#endif /* BITCOIN_H */