[Makefile] Add debug-msan target

Makefile

@@ -34,6 +34,14 @@ debug:
 	rm -f build
 	$(MAKE) build BUILDTYPE=$@
 
+.PHONY: debug-msan
+debug-msan: export CC = clang
+debug-msan: export CXX = clang++
+debug-msan:
+	rm -f build
+	$(MAKE) build BUILDTYPE=debug BUILDDIR=$@ \
+		EMPER_B_SANITIZE=memory EMPER_B_LUNDEF=false
+
 .PHONY: fast-static-analysis
 fast-static-analysis: all check-format check-license doc