Makefile: create symlink to non-default HOST_DIR

If BR2_HOST_DIR is not the default, it can be difficult to find the
host directory (i.e., HOST_DIR always has to be passed explicitly in
addition to the output directory). For example, the Eclipse plugin
assumes that HOST_DIR=BASE_DIR/host.

Create a symlink from $(BASE_DIR)/host to $(HOST_DIR) if it is not the
default. Also remove it in the clean target.

When BR2_HOST_DIR is the default, HOST_DIR_SYMLINK will be empty so
there will be no additional dependency to dirs and nothing to remove
in clean.

Fixes https://bugs.busybox.net/show_bug.cgi?id=10151

Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

Makefile

@@ -445,6 +445,12 @@ TAR_OPTIONS = $(call qstrip,$(BR2_TAR_OPTIONS)) -xf
 # packages compiled for the host go here
 HOST_DIR := $(call qstrip,$(BR2_HOST_DIR))
 
+ifneq ($(HOST_DIR),$(BASE_DIR)/host)
+HOST_DIR_SYMLINK = $(BASE_DIR)/host
+$(HOST_DIR_SYMLINK): $(BASE_DIR)
+	ln -snf $(HOST_DIR) $(BASE_DIR)/host
+endif
+
 # Quotes are needed for spaces and all in the original PATH content.
 BR_PATH = "$(HOST_DIR)/bin:$(HOST_DIR)/sbin:$(PATH)"
 
@@ -548,7 +554,7 @@ endif
 
 .PHONY: dirs
 dirs: $(BUILD_DIR) $(STAGING_DIR) $(TARGET_DIR) \
-	$(HOST_DIR) $(BINARIES_DIR)
+	$(HOST_DIR) $(HOST_DIR_SYMLINK) $(BINARIES_DIR)
 
 $(BUILD_DIR)/buildroot-config/auto.conf: $(BR2_CONFIG)
 	$(MAKE1) $(EXTRAMAKEARGS) HOSTCC="$(HOSTCC_NOCCACHE)" HOSTCXX="$(HOSTCXX_NOCCACHE)" silentoldconfig
@@ -968,7 +974,7 @@ printvars:
 
 .PHONY: clean
 clean:
-	rm -rf $(TARGET_DIR) $(BINARIES_DIR) $(HOST_DIR) \
+	rm -rf $(TARGET_DIR) $(BINARIES_DIR) $(HOST_DIR) $(HOST_DIR_SYMLINK) \
 		$(BUILD_DIR) $(BASE_DIR)/staging \
 		$(LEGAL_INFO_DIR) $(GRAPHS_DIR)