Separate some AC_SUBST / AC_DEFINE

Eventually, the RTS configure alone will need the vast majority of
AC_DEFINE, and the top-level configure will need the most AC_SUBST. By
removing the "side effects" of the macros like this we make them more
reusable so they can be shared between the two configures without doing
too much.

configure.ac

@@ -799,6 +799,9 @@ FP_GCC_EXTRA_FLAGS
 dnl ** look to see if we have a C compiler using an llvm back end.
 dnl
 FP_CC_LLVM_BACKEND
+AS_IF([test x"$CcLlvmBackend" = x"YES"],
+  [AC_DEFINE([CC_LLVM_BACKEND], [1], [Define (to 1) if C compiler has an LLVM back end])])
+AC_SUBST(CcLlvmBackend)
 
 FPTOOLS_SET_C_LD_FLAGS([target],[CFLAGS],[LDFLAGS],[IGNORE_LINKER_LD_FLAGS],[CPPFLAGS])
 FPTOOLS_SET_C_LD_FLAGS([build],[CONF_CC_OPTS_STAGE0],[CONF_GCC_LINKER_OPTS_STAGE0],[CONF_LD_LINKER_OPTS_STAGE0],[CONF_CPP_OPTS_STAGE0])
@@ -1183,6 +1186,13 @@ FPTOOLS_FLOAT_WORD_ORDER_BIGENDIAN
 
 dnl ** check for leading underscores in symbol names
 FP_LEADING_UNDERSCORE
+AC_SUBST([LeadingUnderscore], [`echo $fptools_cv_leading_underscore | sed 'y/yesno/YESNO/'`])
+if test x"$fptools_cv_leading_underscore" = xyes; then
+   AC_SUBST([CabalLeadingUnderscore],[True])
+   AC_DEFINE([LEADING_UNDERSCORE], [1], [Define to 1 if C symbols have a leading underscore added by the compiler.])
+else
+   AC_SUBST([CabalLeadingUnderscore],[False])
+fi
 
 FP_VISIBILITY_HIDDEN
 

m4/fp_cc_llvm_backend.m4

@@ -5,14 +5,12 @@ AC_DEFUN([FP_CC_LLVM_BACKEND],
    AC_MSG_CHECKING([whether C compiler has an LLVM back end])
    $CC -x c /dev/null -dM -E > conftest.txt 2>&1
    if grep "__llvm__" conftest.txt >/dev/null 2>&1; then
-     AC_DEFINE([CC_LLVM_BACKEND], [1], [Define (to 1) if C compiler has an LLVM back end])
      CcLlvmBackend=YES
      AC_MSG_RESULT([yes])
    else
      CcLlvmBackend=NO
      AC_MSG_RESULT([no])
    fi
-   AC_SUBST(CcLlvmBackend)
 
    rm -f conftest.txt
 ])

m4/fp_leading_underscore.m4

@@ -46,11 +46,4 @@ char **argv;
 }]])],[fptools_cv_leading_underscore=yes],[fptools_cv_leading_underscore=no],[fptools_cv_leading_underscore=no])
 ;;
 esac]);
-AC_SUBST([LeadingUnderscore], [`echo $fptools_cv_leading_underscore | sed 'y/yesno/YESNO/'`])
-if test x"$fptools_cv_leading_underscore" = xyes; then
-   AC_SUBST([CabalLeadingUnderscore],[True])
-   AC_DEFINE([LEADING_UNDERSCORE], [1], [Define to 1 if C symbols have a leading underscore added by the compiler.])
-else
-   AC_SUBST([CabalLeadingUnderscore],[False])
-fi
 ])# FP_LEADING_UNDERSCORE