Update makefile to install into STEAMPIPE_INSTALL_DIR if set

(cherry picked from commit 44d62d4)

Author: pdecat

Makefile

@@ -1,12 +1,14 @@
 # Makefile
 
+STEAMPIPE_INSTALL_DIR ?= ~/.steampipe
+
 PLATFORM=$(shell uname)
 
 install: build
 	if test -d ~/.steampipe/db/14.2.0; then \
-		cp ./build-$(PLATFORM)/steampipe_postgres_fdw--1.0.sql ~/.steampipe/db/14.2.0/postgres/share/postgresql/extension/; \
-		cp ./build-$(PLATFORM)/steampipe_postgres_fdw.control ~/.steampipe/db/14.2.0/postgres/share/postgresql/extension/; \
-		cp ./build-$(PLATFORM)/steampipe_postgres_fdw.so ~/.steampipe/db/14.2.0/postgres/lib/postgresql/; \
+		cp ./build-$(PLATFORM)/steampipe_postgres_fdw--1.0.sql $(STEAMPIPE_INSTALL_DIR)/db/14.2.0/postgres/share/postgresql/extension/; \
+		cp ./build-$(PLATFORM)/steampipe_postgres_fdw.control $(STEAMPIPE_INSTALL_DIR)/db/14.2.0/postgres/share/postgresql/extension/; \
+		cp ./build-$(PLATFORM)/steampipe_postgres_fdw.so $(STEAMPIPE_INSTALL_DIR)/db/14.2.0/postgres/lib/postgresql/; \
 	fi
 
 build: prebuild.go