Build vitastor driver as part of the QEMU package by default

Old behaviour can be restored with cmake var WITH_QEMU=true

src/CMakeLists.txt

@@ -4,7 +4,7 @@ project(vitastor)
 
 include(GNUInstallDirs)
 
-set(WITH_QEMU true CACHE BOOL "Build QEMU driver")
+set(WITH_QEMU false CACHE BOOL "Build QEMU driver inside Vitastor source tree")
 set(WITH_FIO true CACHE BOOL "Build FIO driver")
 set(QEMU_PLUGINDIR qemu CACHE STRING "QEMU plugin directory suffix (qemu-kvm on RHEL)")
 set(WITH_ASAN false CACHE BOOL "Build with AddressSanitizer")
@@ -171,6 +171,7 @@ if (${WITH_QEMU})
 	add_library(qemu_vitastor SHARED
 		qemu_driver.c
 	)
+	target_compile_options(qemu_vitastor PUBLIC -DVITASTOR_SOURCE_TREE)
 	target_include_directories(qemu_vitastor PUBLIC
 		../qemu/b/qemu
 		../qemu/include

src/qemu_driver.c

@@ -3,8 +3,10 @@
 
 // QEMU block driver
 
+#ifdef VITASTOR_SOURCE_TREE
 #define BUILD_DSO
 #define _GNU_SOURCE
+#endif
 #include "qemu/osdep.h"
 #include "block/block_int.h"
 #include "qapi/error.h"
@@ -32,6 +34,7 @@
 
 #include "vitastor_c.h"
 
+#ifdef VITASTOR_SOURCE_TREE
 void qemu_module_dummy(void)
 {
 }
@@ -39,6 +42,7 @@ void qemu_module_dummy(void)
 void DSO_STAMP_FUN(void)
 {
 }
+#endif
 
 typedef struct VitastorClient
 {