Support configure flag --with-system-libblkmaker to allow building without the bundled copy

Makefile.am

@@ -26,6 +26,10 @@ bfgminer_CPPFLAGS += @JANSSON_CFLAGS@
 bfgminer_CPPFLAGS += $(PTHREAD_FLAGS)
 bfgminer_CPPFLAGS += $(NCURSES_CPPFLAGS)
 
+bfgminer_LDADD += $(libblkmaker_LIBS)
+bfgminer_LDFLAGS += $(libblkmaker_LDFLAGS)
+bfgminer_CPPFLAGS += $(libblkmaker_CFLAGS)
+
 # common sources
 bfgminer_SOURCES := miner.c
 
@@ -37,9 +41,6 @@ bfgminer_DEPENDENCIES =
 
 if NEED_LIBBLKMAKER
 SUBDIRS           += libblkmaker
-bfgminer_CPPFLAGS += -Ilibblkmaker
-bfgminer_LDFLAGS  += -Llibblkmaker/.libs -Wl,-rpath,libblkmaker/.libs
-bfgminer_LDADD    += -lblkmaker_jansson-0.1 -lblkmaker-0.1
 
 if HAVE_CYGWIN
 bfgminer_DEPENDENCIES += cygblkmaker-0.1-0.dll cygblkmaker_jansson-0.1-0.dll

configure.ac

@@ -440,9 +440,25 @@ else
 fi
 
 
-AC_CONFIG_SUBDIRS([libblkmaker])
+AC_ARG_WITH([system-libblkmaker], [AC_HELP_STRING([--with-system-libblkmaker], [Use system libblkmaker rather than bundled one (default disabled)])],[],[with_system_libblkmaker=no])
+if test "x$with_system_libblkmaker" = "xyes"; then
+	PKG_CHECK_MODULES([libblkmaker],[libblkmaker_jansson-0.1],[
+		true
+	],[
+		AC_MSG_ERROR([Could not find system libblkmaker])
+	])
+else
+	libblkmaker_CFLAGS='-Ilibblkmaker'
+	libblkmaker_LDFLAGS='-Llibblkmaker/.libs -Wl,-rpath,libblkmaker/.libs'
+	libblkmaker_LIBS='-lblkmaker_jansson-0.1 -lblkmaker-0.1'
+	AC_CONFIG_SUBDIRS([libblkmaker])
+fi
+AC_SUBST(libblkmaker_CFLAGS)
+AC_SUBST(libblkmaker_LDFLAGS)
+AC_SUBST(libblkmaker_LIBS)
+
 
-AM_CONDITIONAL([NEED_LIBBLKMAKER], [true])
+AM_CONDITIONAL([NEED_LIBBLKMAKER], [test x$with_system_libblkmaker != xyes])
 AM_CONDITIONAL([NEED_DYNCLOCK], [test x$icarus$modminer$x6500$ztex != xnonono])
 AM_CONDITIONAL([NEED_FPGAUTILS], [test x$avalon$icarus$bitforce$modminer$x6500$ztex != xnononono])
 AM_CONDITIONAL([HAS_SCRYPT], [test x$scrypt = xyes])