[electrs] Support out-of-source-tree build

Makefile.am

@@ -79,7 +79,7 @@ $(OSX_APP)/Contents/PkgInfo:
 
 $(OSX_APP)/Contents/Resources/empty.lproj:
 	$(MKDIR_P) $(@D)
-	@touch $@ 
+	@touch $@
 
 $(OSX_APP)/Contents/Info.plist: $(OSX_PLIST)
 	$(MKDIR_P) $(@D)
@@ -218,9 +218,8 @@ endif
 check-formatting:
 	$(MAKE) -C src $@
 
-.PHONY: electrs
-electrs:
-	$(top_srcdir)/contrib/electrs/build_electrs.py
+electrs: ${PWD}/src/electrs
+	$(top_srcdir)/contrib/electrs/build_electrs.py --dst=${PWD}/src
 
 dist_noinst_SCRIPTS = autogen.sh
 

contrib/electrs/build_electrs.py

@@ -17,6 +17,8 @@
         action = "store_true")
 parser.add_argument('--verbose', help='Sets log level to DEBUG',
         action = "store_true")
+parser.add_argument('--dst', help='Where to copy produced binary',
+    default=os.path.join(ROOT_DIR, "src"))
 args = parser.parse_args()
 
 level = logging.DEBUG if args.verbose else logging.INFO
@@ -47,6 +49,9 @@ def check_dependencies():
         logging.error("You need to install rust (1.28+) https://rustup.rs/")
         bail("rust not found")
 
+    if not os.path.isdir(args.dst):
+        bail("--dst provided '%s' is not a directory", args.dst)
+
 def clone_repo():
     import git
     logging.info("Cloning %s to %s", GIT_REPO, ELECTRS_DIR)
@@ -109,8 +114,7 @@ def cargo_run(args):
 cargo_run(["test", "--release"])
 
 src = os.path.join(ELECTRS_DIR, "target", "release", "electrs")
-dst = os.path.join(ROOT_DIR, "src")
-logging.info("Copying %s to %s", src, dst)
-shutil.copy(src, dst)
+logging.info("Copying %s to %s", src, args.dst)
+shutil.copy(src, args.dst)
 
 logging.info("Done")