Remove libmbedtls file from libbedrock

mbedtls/programs/test/cpp_dummy_build.cpp was being added to libbedrock
by accidental inclusion via `find`

Author: mikefero

Makefile

@@ -67,7 +67,7 @@ STUFFC = $(shell find libstuff -name '*.c')
 STUFFOBJ = $(STUFFCPP:%.cpp=$(INTERMEDIATEDIR)/%.o) $(STUFFC:%.c=$(INTERMEDIATEDIR)/%.o)
 STUFFDEP = $(STUFFCPP:%.cpp=$(INTERMEDIATEDIR)/%.d)
 
-LIBBEDROCKCPP = $(shell find * -name '*.cpp' -not -name main.cpp -not -path 'test*' -not -path 'libstuff*')
+LIBBEDROCKCPP = $(shell find * -name '*.cpp' -not -name main.cpp -not -path 'test*' -not -path 'libstuff*' -not -path 'mbedtls*')
 LIBBEDROCKOBJ = $(LIBBEDROCKCPP:%.cpp=$(INTERMEDIATEDIR)/%.o)
 LIBBEDROCKDEP = $(LIBBEDROCKCPP:%.cpp=$(INTERMEDIATEDIR)/%.d)