fix: makefile unable to convert the src/%.c paths into obj/$arch/$prof/%.o paths

had to include the src/ path in the shell finding, due to it otherwise
prefixing with ./src (it was aparrently also including files from
target/)

makefile

@@ -53,7 +53,7 @@ BIN       := $(DIR_BIN)/$(NAME)$(EXT)
 C_SRC  := $(shell find src/ -name '*.c')
 C_OBJ  := $(patsubst src/%,$(DIR_OBJ)/%,$(C_SRC:.c=.o))
 C_DEP  := $(C_OBJ:.o=.d)
-RS_SRC := $(shell find -name '*.rs')
+RS_SRC := $(shell find src/ -name '*.rs')
 RS_LIB := $(RSOUT)/libmcaselector_lite.a
 RS_DEP := $(RSOUT)/libmcaselector_lite.d
 RSOUT  :=
@@ -109,6 +109,9 @@ else
 compile_commands.json:
 endif
 
+# disable implicit rules
+.SUFFIXES:
+
 # include the dependencies
 -include $(C_DEP)
 -include $(RS_DEP)