build: move BEES_VERSION to a separate C file to avoid unnecessary building

Every git commit was causing bees.cc and bees-hash.cc to be rebuilt,
which was expensive and unnecessary.

Signed-off-by: Zygo Blaxell <bees@furryterror.org>

src/.gitignore

@@ -1 +1 @@
-bees-version.h
+bees-version.[ch]

src/Makefile

@@ -11,8 +11,8 @@ LIBS = -lcrucible -lpthread
 LDFLAGS = -L../lib -Wl,-rpath=$(shell realpath ../lib)
 
 depends.mk: Makefile *.cc
-	echo "#define BEES_VERSION \"$(shell git describe --always --dirty || echo UNKNOWN)\"" > bees-version.new.h
-	mv -f bees-version.new.h bees-version.h
+	echo "const char *BEES_VERSION = \"$(shell git describe --always --dirty || echo UNKNOWN)\";" > bees-version.new.c
+	mv -f bees-version.new.c bees-version.c
 	for x in *.cc; do $(CXX) $(CXXFLAGS) -M "$$x"; done > depends.mk.new
 	mv -fv depends.mk.new depends.mk
 
@@ -33,9 +33,11 @@ BEES_OBJS = \
 	bees-roots.o \
 	bees-thread.o \
 	bees-types.o \
+	bees-version.o \
 
 ../bin/bees: $(BEES_OBJS)
 	$(CXX) $(CXXFLAGS) -o "$@" $(BEES_OBJS) $(LDFLAGS) $(LIBS)
 
 clean:
-	-rm -fv *.o bees-version.h
+	-rm -fv bees-version.h
+	-rm -fv *.o bees-version.c

src/bees-hash.cc

@@ -1,4 +1,3 @@
-#include "bees-version.h"
 #include "bees.h"
 
 #include "crucible/crc64.h"

src/bees.cc

@@ -1,4 +1,3 @@
-#include "bees-version.h"
 #include "bees.h"
 
 #include "crucible/limits.h"

src/bees.h

@@ -819,6 +819,7 @@ public:
 };
 
 // And now, a giant pile of extern declarations
+extern const char *BEES_VERSION;
 string pretty(double d);
 extern RateLimiter bees_info_rate_limit;
 void bees_sync(int fd);