Makefile: fix bashism in NO_PYTHON

== is a bash extension; in shell it's a single =:

```
/bin/sh: 1: [: unexpected operator
sql-rewrite wallet/db_postgres_sqlgen.c
```

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Makefile

@@ -282,22 +282,22 @@ SHA256STAMP = echo '$(1) SHA256STAMP:'`cat $(sort $(filter-out FORCE,$^)) | $(SH
 
 # generate-wire.py --page [header|impl] hdrfilename wirename < csv > file
 %_wiregen.h: %_wire.csv $(WIRE_GEN_DEPS)
-	@if $(call SHA256STAMP_CHANGED); then if [ "$$NO_PYTHON" == 1 ]; then echo "Error: NO_PYTHON on $@"; exit 1; fi; \
+	@if $(call SHA256STAMP_CHANGED); then if [ "$$NO_PYTHON" = 1 ]; then echo "Error: NO_PYTHON on $@"; exit 1; fi; \
 		$(call VERBOSE,"wiregen $@",tools/generate-wire.py --page header $($@_args) $@ `basename $< .csv | sed 's/_exp_/_/'` < $< > $@ && $(call SHA256STAMP,//)); \
 	fi
 
 %_wiregen.c: %_wire.csv $(WIRE_GEN_DEPS)
-	@if $(call SHA256STAMP_CHANGED); then if [ "$$NO_PYTHON" == 1 ]; then echo "Error: NO_PYTHON on $@"; exit 1; fi; \
+	@if $(call SHA256STAMP_CHANGED); then if [ "$$NO_PYTHON" = 1 ]; then echo "Error: NO_PYTHON on $@"; exit 1; fi; \
 		$(call VERBOSE,"wiregen $@",tools/generate-wire.py --page impl $($@_args) ${@:.c=.h} `basename $< .csv | sed 's/_exp_/_/'` < $< > $@ && $(call SHA256STAMP,//)); \
 	fi
 
 %_printgen.h: %_wire.csv $(WIRE_GEN_DEPS)
-	@if $(call SHA256STAMP_CHANGED); then if [ "$$NO_PYTHON" == 1 ]; then echo "Error: NO_PYTHON on $@"; exit 1; fi; \
+	@if $(call SHA256STAMP_CHANGED); then if [ "$$NO_PYTHON" = 1 ]; then echo "Error: NO_PYTHON on $@"; exit 1; fi; \
 		$(call VERBOSE,"printgen $@",tools/generate-wire.py -s -P --page header $($@_args) $@ `basename $< .csv | sed 's/_exp_/_/'` < $< > $@ && $(call SHA256STAMP,//)); \
 	fi
 
 %_printgen.c: %_wire.csv $(WIRE_GEN_DEPS)
-	@if $(call SHA256STAMP_CHANGED); then  if [ "$$NO_PYTHON" == 1 ]; then echo "Error: NO_PYTHON on $@"; exit 1; fi; \
+	@if $(call SHA256STAMP_CHANGED); then  if [ "$$NO_PYTHON" = 1 ]; then echo "Error: NO_PYTHON on $@"; exit 1; fi; \
 		$(call VERBOSE,"printgen $@",tools/generate-wire.py -s -P --page impl $($@_args) ${@:.c=.h} `basename $< .csv | sed 's/_exp_/_/'` < $< > $@ && $(call SHA256STAMP,//)); \
 	fi
 

wallet/Makefile

@@ -37,12 +37,12 @@ SQL_FILES := 				\
 	wallet/test/run-wallet.c	\
 
 wallet/statements_gettextgen.po: $(SQL_FILES) FORCE
-	@if $(call SHA256STAMP_CHANGED); then if [ "$$NO_PYTHON" == 1 ]; then echo "Error: NO_PYTHON on $@"; exit 1; fi; \
+	@if $(call SHA256STAMP_CHANGED); then if [ "$$NO_PYTHON" = 1 ]; then echo "Error: NO_PYTHON on $@"; exit 1; fi; \
 		$(call VERBOSE,"xgettext $@",xgettext -kNAMED_SQL -kSQL --add-location --no-wrap --omit-header -o $@ $(SQL_FILES) && $(call SHA256STAMP,# )); \
 	fi
 
 wallet/db_%_sqlgen.c: wallet/statements_gettextgen.po devtools/sql-rewrite.py FORCE
-	@if $(call SHA256STAMP_CHANGED); then if [ "$$NO_PYTHON" == 1 ]; then echo "Error: NO_PYTHON on $@"; exit 1; fi; \
+	@if $(call SHA256STAMP_CHANGED); then if [ "$$NO_PYTHON" = 1 ]; then echo "Error: NO_PYTHON on $@"; exit 1; fi; \
 		$(call VERBOSE,"sql-rewrite $@",devtools/sql-rewrite.py wallet/statements_gettextgen.po $* > $@ && $(call SHA256STAMP,//)); \
 	fi