a cpu option of the configure script as a method to specify a target cpu

* don't setup a cpu before scanning for --cpu=
    * --cpu= option sets a 'cpu' variable, not a 'build_cpu', 'build_cpu' was not used anywhere.
    * if cpu="" and ARCH != "" then cpu=$ARCH else cpu=`uname -m`
    * replace "Build CPU" with "Target CPU" in the output of the configure script.
      output this value only when not builing a cross compilers.
    * remove a HOST_I386, ... defines from a config.h file.
      thise defines are not used anywhere and cpu is now used to define a target cpu

configure

@@ -46,8 +46,7 @@ tcc_crtprefix=""
 tcc_elfinterp=""
 tcc_lddir=
 confvars=
-
+cpu=
-cpu=`uname -m`
 
 # OS specific
 targetos=`uname -s`
@@ -166,7 +165,7 @@ for opt do
   ;;
   --extra-libs=*) extralibs=${opt#--extra-libs=}
   ;;
-  --cpu=*) build_cpu=`echo $opt | cut -d '=' -f 2`
+  --cpu=*) cpu=`echo $opt | cut -d '=' -f 2`
   ;;
   --enable-gprof) gprof="yes"
   ;;
@@ -195,6 +194,13 @@ for opt do
   esac
 done
 
+if test -z "$cpu" ; then
+    if test -n "$ARCH" ; then
+	cpu="$ARCH"
+    else
+	cpu=`uname -m`
+    fi
+fi
 classify_cpu "$cpu"
 
 # Checking for CFLAGS
@@ -357,24 +363,24 @@ else
   esac
 fi
 
-cat <<EOF
+echo "Binary  directory   $bindir"
-Binary  directory   $bindir
+echo "TinyCC directory    $tccdir"
-TinyCC directory    $tccdir
+echo "Library directory   $libdir"
-Library directory   $libdir
+echo "Include directory   $includedir"
-Include directory   $includedir
+echo "Manual directory    $mandir"
-Manual directory    $mandir
+echo "Info directory      $infodir"
-Info directory      $infodir
+echo "Doc directory       $docdir"
-Doc directory       $docdir
+echo "Target root prefix  $sysroot"
-Target root prefix  $sysroot
+echo "Source path      $source_path"
-Source path      $source_path
+echo "C compiler       $cc"
-C compiler       $cc
+echo "cross compilers  $build_cross"
-Build CPU        $cpu
+if test "$build_cross" = "no"; then
-Target OS        $targetos
+echo "Target CPU       $cpu"
-Big Endian       $bigendian
+fi
-gprof enabled    $gprof
+echo "Target OS        $targetos"
-cross compilers  $build_cross
+echo "Big Endian       $bigendian"
-use libgcc       $use_libgcc
+echo "gprof enabled    $gprof"
-EOF
+echo "use libgcc       $use_libgcc"
 
 echo "Creating config.mak and config.h"
 
@@ -430,29 +436,21 @@ echo "#define GCC_MINOR $gcc_minor" >> $TMPH
 
 if test "$cpu" = "x86" ; then
   echo "ARCH=i386" >> config.mak
-  echo "#define HOST_I386 1" >> $TMPH
 elif test "$cpu" = "x86-64" ; then
   echo "ARCH=x86-64" >> config.mak
-  echo "#define HOST_X86_64 1" >> $TMPH
 elif test "$cpu" = "armv4l" ; then
   echo "ARCH=arm" >> config.mak
-  echo "#define HOST_ARM 1" >> $TMPH
   echo "#define TCC_ARM_VERSION $cpuver" >> $TMPH
 elif test "$cpu" = "aarch64" ; then
   echo "ARCH=arm64" >> config.mak
-  echo "#define HOST_ARM64 1" >> $TMPH
 elif test "$cpu" = "powerpc" ; then
   echo "ARCH=ppc" >> config.mak
-  echo "#define HOST_PPC 1" >> $TMPH
 elif test "$cpu" = "mips" ; then
   echo "ARCH=mips" >> config.mak
-  echo "#define HOST_MIPS 1" >> $TMPH
 elif test "$cpu" = "s390" ; then
   echo "ARCH=s390" >> config.mak
-  echo "#define HOST_S390 1" >> $TMPH
 elif test "$cpu" = "alpha" ; then
   echo "ARCH=alpha" >> config.mak
-  echo "#define HOST_ALPHA 1" >> $TMPH
 else
   echo "Unsupported CPU"
   exit 1