Allow faster rebuilds in certain cases

Previously, when rebuilding with a different "--prefix" or "--scriptdir",
all Bro source files were recompiled.  With this change, only util.cc
is recompiled.  Instead of specifying command-line preprocessor
macros on all source files, a header file is regenerated when needed
which only util.cc includes.

src/CMakeLists.txt

@@ -4,6 +4,7 @@ include_directories(BEFORE
 )
 
 configure_file(version.c.in ${CMAKE_CURRENT_BINARY_DIR}/version.c)
+configure_file(util-config.h.in ${CMAKE_CURRENT_BINARY_DIR}/util-config.h)
 
 # This creates a custom command to transform a bison output file (inFile)
 # into outFile in order to avoid symbol conflicts:
@@ -444,10 +445,6 @@ set(bro_SRCS
 
 collect_headers(bro_HEADERS ${bro_SRCS})
 
-add_definitions(-DBRO_SCRIPT_INSTALL_PATH="${BRO_SCRIPT_INSTALL_PATH}")
-add_definitions(-DBRO_SCRIPT_SOURCE_PATH="${BRO_SCRIPT_SOURCE_PATH}")
-add_definitions(-DBRO_BUILD_PATH="${CMAKE_CURRENT_BINARY_DIR}")
-
 add_executable(bro ${bro_SRCS} ${bro_HEADERS})
 
 target_link_libraries(bro ${brodeps} ${CMAKE_THREAD_LIBS_INIT})

src/util-config.h.in

@@ -0,0 +1,3 @@
+#define BRO_SCRIPT_INSTALL_PATH "@BRO_SCRIPT_INSTALL_PATH@"
+#define BRO_SCRIPT_SOURCE_PATH "@BRO_SCRIPT_SOURCE_PATH@"
+#define BRO_BUILD_PATH "@CMAKE_CURRENT_BINARY_DIR@"

src/util.cc

@@ -1,6 +1,7 @@
 // See the file "COPYING" in the main distribution directory for copyright.
 
 #include "config.h"
+#include "util-config.h"
 
 #ifdef TIME_WITH_SYS_TIME
 # include <sys/time.h>