package/scons: bring back Python interpreter call in SCONS variable

Back in commit
f72be49830 ("package/scons: remove
python from SCONS"), we changed the SCONS variable to not explicitly
invoke the Python interpreter, because some scons-based packages used
python2, some python3.

Now that the 3 remaining packages using scons (gpsd, mongodb and
benejson) all use python3, we can bring back the python3 interpreter
call into the SCONS variable, and slightly simplify those packages.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/benejson/benejson.mk

@@ -41,7 +41,7 @@ endif # Shared enabled
 define BENEJSON_BUILD_CMDS
 	(cd $(@D); \
 		$(TARGET_CONFIGURE_OPTS) CROSS=$(TARGET_CROSS) \
-		$(HOST_DIR)/bin/python3 $(SCONS) $(BENEJSON_SCONS_TARGETS))
+		$(SCONS) $(BENEJSON_SCONS_TARGETS))
 endef
 
 define BENEJSON_INSTALL_STAGING_CMDS

package/gpsd/gpsd.mk

@@ -211,7 +211,7 @@ GPSD_SCONS_ENV += \
 define GPSD_BUILD_CMDS
 	(cd $(@D); \
 		$(GPSD_SCONS_ENV) \
-		$(HOST_DIR)/bin/python3 $(SCONS) \
+		$(SCONS) \
 		$(GPSD_SCONS_OPTS))
 endef
 
@@ -219,7 +219,7 @@ define GPSD_INSTALL_TARGET_CMDS
 	(cd $(@D); \
 		$(GPSD_SCONS_ENV) \
 		DESTDIR=$(TARGET_DIR) \
-		$(HOST_DIR)/bin/python3 $(SCONS) \
+		$(SCONS) \
 		$(GPSD_SCONS_OPTS) \
 		$(if $(BR2_PACKAGE_HAS_UDEV),udev-install,install))
 endef
@@ -241,7 +241,7 @@ define GPSD_INSTALL_STAGING_CMDS
 	(cd $(@D); \
 		$(GPSD_SCONS_ENV) \
 		DESTDIR=$(STAGING_DIR) \
-		$(HOST_DIR)/bin/python3 $(SCONS) \
+		$(SCONS) \
 		$(GPSD_SCONS_OPTS) \
 		install)
 endef

package/mongodb/mongodb.mk

@@ -86,7 +86,7 @@ endif
 
 define MONGODB_BUILD_CMDS
 	(cd $(@D); \
-		$(HOST_DIR)/bin/python3 $(SCONS) \
+		$(SCONS) \
 		$(MONGODB_SCONS_ENV) \
 		$(MONGODB_SCONS_OPTS) \
 		$(MONGODB_SCONS_TARGETS))
@@ -94,7 +94,7 @@ endef
 
 define MONGODB_INSTALL_TARGET_CMDS
 	(cd $(@D); \
-		$(HOST_DIR)/bin/python3 $(SCONS) \
+		$(SCONS) \
 		$(MONGODB_SCONS_ENV) \
 		$(MONGODB_SCONS_OPTS) \
 		--prefix=$(TARGET_DIR)/usr \

package/scons/scons.mk

@@ -18,4 +18,4 @@ HOST_SCONS_INSTALL_OPTS = \
 $(eval $(host-python-package))
 
 # variables used by other packages
-SCONS = $(HOST_DIR)/bin/scons $(if $(QUIET),-s)
+SCONS = $(HOST_DIR)/bin/python3 $(HOST_DIR)/bin/scons $(if $(QUIET),-s)