Makefile: only use dune --release on release builds

We were setting this flag for stage2, as it increases optimizations used
for the compiler we mostly care about. But this is too slow for normally
edit-debug loops, and for little gain. So change the logic to only use
--release if we are in fact building a release (or nightly build).

Makefile

@@ -170,7 +170,7 @@ $(FSTAR1_FULL_EXE): .bare1.src.touch .full1.src.touch .stage1.ml.touch $(MAYBEFO
 
 $(FSTAR2_BARE_EXE): .bare2.src.touch .stage2.ml.touch $(MAYBEFORCE)
 	$(call bold_msg, "BUILD", "STAGE 2 FSTARC-BARE")
-	$(MAKE) -C stage2 fstarc-bare FSTAR_DUNE_RELEASE=1
+	$(MAKE) -C stage2 fstarc-bare
 	touch -c $@
 	# ^ Note, even if we don't release fstar-bare itself,
 	# it is still part of the build of the full fstar, so
@@ -191,7 +191,7 @@ $(FSTAR2_BARE_EXE): .bare2.src.touch .stage2.ml.touch $(MAYBEFORCE)
 
 $(FSTAR2_FULL_EXE): .bare2.src.touch .full2.src.touch .stage2.ml.touch $(MAYBEFORCE)
 	$(call bold_msg, "BUILD", "STAGE 2 FSTARC")
-	$(MAKE) -C stage2 fstarc-full FSTAR_DUNE_RELEASE=1
+	$(MAKE) -C stage2 fstarc-full
 	touch -c $@
 
 .alib2.src.touch: $(FSTAR2_FULL_EXE) .force
@@ -209,7 +209,7 @@ $(FSTAR2_FULL_EXE): .bare2.src.touch .full2.src.touch .stage2.ml.touch $(MAYBEFO
 
 .alib2.touch: .alib2.src.touch .stage2.ml.touch $(MAYBEFORCE)
 	$(call bold_msg, "BUILD", "STAGE 2 LIB")
-	$(MAKE) -C stage2/ libapp FSTAR_DUNE_RELEASE=1
+	$(MAKE) -C stage2/ libapp
 	touch $@
 
 .plib2.src.touch: $(FSTAR2_FULL_EXE) .alib2.src.touch .force
@@ -229,7 +229,7 @@ $(FSTAR2_FULL_EXE): .bare2.src.touch .full2.src.touch .stage2.ml.touch $(MAYBEFO
 
 .plib2.touch: .plib2.src.touch .stage2.ml.touch $(MAYBEFORCE)
 	$(call bold_msg, "BUILD", "STAGE 2 PLUGLIB")
-	$(MAKE) -C stage2/ libplugin FSTAR_DUNE_RELEASE=1
+	$(MAKE) -C stage2/ libplugin
 	touch $@
 
 # F# library, from stage 2.
@@ -298,7 +298,7 @@ endif
 .install-stage2.touch: export FSTAR_LINK_LIBDIRS=$(LINK_OK)
 .install-stage2.touch: .stage2.src.touch
 	$(call bold_msg, "INSTALL", "STAGE 2")
-	$(MAKE) -C stage2 install PREFIX=$(CURDIR)/stage2/out FSTAR_DUNE_RELEASE=1
+	$(MAKE) -C stage2 install PREFIX=$(CURDIR)/stage2/out
 	@# ^ pass PREFIX to make sure we don't get it from env
 	touch $@
 
@@ -326,14 +326,14 @@ install: export PREFIX?=/usr/local
 install: export FSTAR_LINK_LIBDIRS=0 # default is false, but set anyway
 install:
 	$(call bold_msg, "INSTALL", "STAGE 2")
-	$(MAKE) -C stage2 install FSTAR_DUNE_RELEASE=1
+	$(MAKE) -C stage2 install
 
 __do-install-stage1:
 	$(call bold_msg, "INSTALL", "STAGE 1")
 	$(MAKE) -C stage1 install
 __do-install-stage2:
 	$(call bold_msg, "INSTALL", "STAGE 2")
-	$(MAKE) -C stage2 install FSTAR_DUNE_RELEASE=1
+	$(MAKE) -C stage2 install
 
 __do-archive: .force
 	rm -rf $(PKGTMP)

mk/stage.mk

@@ -7,7 +7,7 @@ FSTAR_DUNE_OPTIONS += --display=quiet
 endif
 
 FSTAR_DUNE_BUILD_OPTIONS := $(FSTAR_DUNE_OPTIONS)
-ifeq ($(FSTAR_DUNE_RELEASE),1)
+ifeq ($(FSTAR_RELEASE),1)
 FSTAR_DUNE_BUILD_OPTIONS += --release
 endif