Remove redundant lines from 'acx_check_cfortran.m4'.

In sync with 'cdipio-dev-snapshot-20210223' now.

m4/acx_check_cfortran.m4

@@ -58,8 +58,6 @@ AC_DEFUN([_ACX_CHECK_CFORTRAN_FC],
            [ACX_MV_OBJ([conftest],[conftest_f])
             save_LIBS=$LIBS
             LIBS="conftest_c.$ac_objext conftest_f.$ac_objext $LIBS"
-            AS_CASE([$FC_FPP_FLAG],[-x\ f??-cpp-input],
-              [LIBS="-x none $LIBS"])
             AC_RUN_IFELSE([AC_LANG_PROGRAM(,
 [      USE conftest_data, ONLY: ri
       IMPLICIT NONE
@@ -144,8 +142,6 @@ AC_DEFUN([_ACX_CHECK_CFORTRAN_F77],
            [ACX_MV_OBJ([conftest],[conftest_f])
             save_LIBS=$LIBS
             LIBS="conftest_c.$ac_objext conftest_f.$ac_objext $LIBS"
-            AS_CASE([$FC_FPP_FLAG],[-x\ f??-cpp-input],
-              [LIBS="-x none $LIBS"])
             AC_RUN_IFELSE([AC_LANG_PROGRAM(,
 [      REAL RI
       COMMON /CFTSTD/ RI