Add linker flags after coreneuron library (clang and -Wl,--as-needed effect)

Author: pramodk

extra/nrnivmodl_core_makefile.in

@@ -84,7 +84,8 @@ endif
 
 CXXFLAGS = @CORENRN_CXX_FLAGS@
 CXX_COMPILE_CMD = $(CXX) $(CXXFLAGS) @CMAKE_CXX_COMPILE_OPTIONS_PIC@ @CORENRN_COMMON_COMPILE_DEFS@ $(INCLUDES)
-CXX_LINK_EXE_CMD = $(CXX) $(CXXFLAGS) @CMAKE_EXE_LINKER_FLAGS@
+CXX_LINK_EXE_CMD = $(CXX) $(CXXFLAGS)
+CXX_LINK_EXE_FLAGS = @CMAKE_EXE_LINKER_FLAGS@
 CXX_SHARED_LIB_CMD = $(CXX) $(CXXFLAGS) @CMAKE_SHARED_LIBRARY_CREATE_CXX_FLAGS@ @CMAKE_SHARED_LIBRARY_CXX_FLAGS@ @CMAKE_SHARED_LINKER_FLAGS@
 
 # ISPC compilation and link commands
@@ -210,9 +211,9 @@ endif
 # main target to build binary
 $(SPECIAL_EXE): coremech_lib_target
 	@printf " => $(C_GREEN)Binary$(C_RESET) creating $(SPECIAL_EXE)\n"
-	$(CXX_LINK_EXE_CMD) -o $(SPECIAL_EXE) $(CORENRN_SHARE_CORENRN_DIR)/coreneuron.cpp \
+	  $(CXX_LINK_EXE_CMD) -o $(SPECIAL_EXE) $(CORENRN_SHARE_CORENRN_DIR)/coreneuron.cpp \
 	  -I$(CORENRN_INC_DIR) $(INCFLAGS) \
-	  -L$(OUTPUT_DIR) -l$(COREMECH_LIB_NAME) $(CORENRNLIB_FLAGS) $(LDFLAGS) \
+	  -L$(OUTPUT_DIR) -l$(COREMECH_LIB_NAME) $(CORENRNLIB_FLAGS) $(LDFLAGS) $(CXX_LINK_EXE_FLAGS) \
 	  -Wl,-rpath,'$(LIB_RPATH)' -Wl,-rpath,$(CORENRN_LIB_DIR) -Wl,-rpath,'$(INSTALL_LIB_RPATH)'
 
 coremech_lib_target: $(corenrnmech_lib_target)