Remove custom Make rule. (NFC)

<rdar://problem/64913338>

Author: adrian-prantl

lldb/test/API/lang/swift/clangimporter/objcmain_conflicting_dylibs/Makefile

@@ -12,10 +12,10 @@ ifneq "$(CODESIGN)" ""
 endif
 
 lib%.dylib: %.swift
-	$(SWIFTC) -g -Onone $^ -emit-library -module-name $(shell basename $< .swift) -emit-module -Xlinker -install_name -Xlinker @executable_path/$@ -Xcc -I$(SRCDIR) -Xcc -I$(SRCDIR)/$(shell basename $< .swift) $(SWIFTFLAGS) -emit-objc-header-path $(shell basename $< .swift).h
-ifneq "$(CODESIGN)" ""
-	$(CODESIGN) -s - "$@"
-endif
+	mkdir -p $(BUILDDIR)/$(shell basename $< .swift)
+	$(MAKE) MAKE_DSYM=YES \
+		DYLIB_NAME=$(shell basename $< .swift) \
+		VPATH=$(SRCDIR) -I $(SRCDIR) -f $(SRCDIR)/dylib.mk all
 
 clean::
 	rm -rf *.swiftmodule *.swiftdoc *.dSYM *~ lib*.dylib a.out *.o

lldb/test/API/lang/swift/clangimporter/objcmain_conflicting_dylibs/dylib.mk

@@ -0,0 +1,6 @@
+DYLIB_ONLY := YES
+DYLIB_SWIFT_SOURCES := $(DYLIB_NAME).swift
+SWIFT_OBJC_HEADER = $(DYLIB_NAME).h
+SWIFTFLAGS_EXTRAS = -Xcc -I$(SRCDIR) -I$(SRCDIR)/$(DYLIB_NAME)
+
+include Makefile.rules