ppa: Adapt the Makefile to work when building a PPA

Signed-off-by: Christian Decker <decker.christian@gmail.com>

external/Makefile

@@ -48,7 +48,7 @@ endif
 EXTERNAL_LDLIBS := -L${TARGET_DIR} $(patsubst lib%.a,-l%,$(notdir $(EXTERNAL_LIBS)))
 
 submodcheck: FORCE
-	@tools/refresh-submodules.sh $(SUBMODULES)
+	echo submodcheck disabled
 
 $(EXTERNAL_HEADERS): submodcheck
 
@@ -59,7 +59,7 @@ $(TARGET_DIR)/libsodium.a: $(TARGET_DIR)/libsodium-build/src/libsodium/libsodium
 $(TARGET_DIR)/libsodium-build/src/libsodium/libsodium.la: external/libsodium/src/libsodium/include/sodium.h
 	cd external/libsodium && ./autogen.sh
 	mkdir -p ${TARGET_DIR}/libsodium-build
-	cd $(TARGET_DIR)/libsodium-build && $(TOP)/libsodium/configure CC="$(CC)" --enable-static=yes $(CROSSCOMPILE_OPTS) --enable-shared=no --prefix=/ --libdir=/ && $(MAKE)
+	cd $(TARGET_DIR)/libsodium-build && $(TOP)/libsodium/configure CC="$(CC)" CFLAGS=-Wno-error --enable-static=yes $(CROSSCOMPILE_OPTS) --enable-shared=no --enable-tests=no --prefix=/ --libdir=/ && $(MAKE)
 
 # libsecp included in libwally.
 # Wildcards here are magic.  See http://stackoverflow.com/questions/2973445/gnu-makefile-rule-generating-a-few-targets-from-a-single-source-file
@@ -90,8 +90,8 @@ $(TARGET_DIR)/libjsmn.a: $(TARGET_DIR)/jsmn-build/jsmn.o
 
 # Need separate build dir: changes inside submodule make git think it's dirty.
 $(TARGET_DIR)/libbacktrace.a: external/libbacktrace/backtrace.h
-	mkdir -p $(TARGET_DIR)/libbacktrace-build
-	cd $(TARGET_DIR)/libbacktrace-build && $(TOP)/libbacktrace/configure CC="$(CC)" --enable-static=yes $(CROSSCOMPILE_OPTS) --enable-shared=no --prefix=/ --libdir=/ && $(MAKE)
+	@mkdir $(TARGET_DIR)/libbacktrace-build 2>/dev/null || true
+	cd $(TARGET_DIR)/libbacktrace-build && $(TOP)/libbacktrace/configure CC="$(CC)" CFLAGS=-Wno-error --enable-static=yes $(CROSSCOMPILE_OPTS) --enable-shared=no --prefix=/ --libdir=/ && $(MAKE)
 	$(MAKE) -C $(TARGET_DIR)/libbacktrace-build DESTDIR=$$(pwd)/$(TARGET_DIR) install-exec
 
 distclean: external-distclean