Add support for the new generation flang that comes with LLVM17

Author: martin-frbg

Makefile.system

@@ -1087,8 +1087,9 @@ endif
 endif
 endif
 
-ifeq ($(F_COMPILER), GFORTRAN)
+ifeq ($(F_COMPILER), $(filter $(F_COMPILER),GFORTRAN FLANGNEW))
 CCOMMON_OPT += -DF_INTERFACE_GFORT
+ifeq ($(F_COMPILER), GFORTRAN)
 FCOMMON_OPT += -Wall
 # make single-threaded LAPACK calls thread-safe #1847
 FCOMMON_OPT += -frecursive
@@ -1102,6 +1103,7 @@ EXTRALIB += -lgfortran
 endif
 endif
 endif
+endif
 ifdef NO_BINARY_MODE
 ifeq ($(ARCH), $(filter $(ARCH),mips64))
 ifdef BINARY64