Fix parallel builds

Author: sfackler

Makefile.in

@@ -9,22 +9,29 @@ INSTALL_DIR := %PREFIX%
 ###############################################################################
 PHF_DIR := submodules/rust-phf
 PHF := $(foreach file,$(shell $(MAKE) -s -C $(PHF_DIR) print-targets),$(PHF_DIR)/$(file))
+PHF_STAMP := $(BUILDDIR)/phf.stamp
 OPENSSL_DIR := submodules/rust-openssl
 OPENSSL := $(foreach file,$(shell $(MAKE) -s -C $(OPENSSL_DIR) print-target),$(OPENSSL_DIR)/$(file))
+OPENSSL_STAMP := $(BUILDDIR)/openssl.stamp
 
-$(PHF):
+$(PHF): $(PHF_STAMP)
+
+$(PHF_STAMP):
 	$(MAKE) -C $(PHF_DIR)
-	touch $(PHF)
+	touch $(PHF_STAMP)
+
+$(OPENSSL): $(OPENSSL_STAMP)
 
-$(OPENSSL):
+$(OPENSSL_STAMP):
 	$(MAKE) -C $(OPENSSL_DIR)
-	touch $(OPENSSL)
+	touch $(OPENSSL_STAMP)
 
 ###############################################################################
 # Main targets
 ###############################################################################
 POSTGRES_LIB_FILE := src/lib.rs
 POSTGRES_LIB := $(foreach file,$(shell $(RUSTC) --crate-file-name $(POSTGRES_LIB_FILE)),$(BUILDDIR)/$(file))
+POSTGRES_STAMP := $(BUILDDIR)/postgres.stamp
 POSTGRES_TEST := $(BUILDDIR)/$(shell $(RUSTC) --test --crate-file-name $(POSTGRES_LIB_FILE))
 
 POSTGRES_LIB_DEPS := $(BUILDDIR)/postgres.d
@@ -38,9 +45,12 @@ LINK_ARGS := $(foreach file,$(OPENSSL),-L $(dir $(file))) $(foreach file,$(PHF),
 $(BUILDDIR):
 	mkdir -p $@
 
-$(POSTGRES_LIB): $(POSTGRES_LIB_FILE) $(PHF) $(OPENSSL) | $(BUILDDIR)
+$(POSTGRES_LIB): $(POSTGRES_STAMP)
+
+$(POSTGRES_STAMP): $(POSTGRES_LIB_FILE) $(PHF) $(OPENSSL) | $(BUILDDIR)
 	$(RUSTC) $(RUSTFLAGS) $(LINK_ARGS) --dep-info $(POSTGRES_LIB_DEPS) \
 		--out-dir $(@D) $<
+	touch $(POSTGRES_STAMP)
 
 $(POSTGRES_TEST): $(POSTGRES_LIB_FILE) $(PHF) $(OPENSSL) | $(BUILDDIR)
 	$(RUSTC) $(RUSTFLAGS) $(LINK_ARGS) --dep-info $(POSTGRES_TEST_DEPS) \