10l: Revert bogus use of GCC's -march=xx:

Almost all CPU targets use -mcpu=xx to set architecture type,
register usage, choice of mnemonics, and instruction
scheduling parameters, except x86, MIPS, HPPA which uses -march=xx

Originally committed as revision 6736 to svn://svn.ffmpeg.org/ffmpeg/trunk

configure

@@ -1051,49 +1051,49 @@ POWERPCMODE="32bits"
 if test $cpu != "generic"; then
     case $cpu in
         601|ppc601|PowerPC601)
-            add_cflags "-march=601"
+            add_cflags "-mcpu=601"
             if test $altivec = "yes"; then
                 echo "WARNING: Tuning for PPC601 but AltiVec enabled!";
             fi
             TUNECPU=ppc601
         ;;
         603*|ppc603*|PowerPC603*)
-            add_cflags "-march=603"
+            add_cflags "-mcpu=603"
             if test $altivec = "yes"; then
                 echo "WARNING: Tuning for PPC603 but AltiVec enabled!";
             fi
             TUNECPU=ppc603
         ;;
         604*|ppc604*|PowerPC604*)
-            add_cflags "-march=604"
+            add_cflags "-mcpu=604"
             if test $altivec = "yes"; then
                 echo "WARNING: Tuning for PPC604 but AltiVec enabled!";
             fi
             TUNECPU=ppc604
         ;;
         G3|g3|75*|ppc75*|PowerPC75*)
-            add_cflags "-march=750 -mpowerpc-gfxopt"
+            add_cflags "-mcpu=750 -mpowerpc-gfxopt"
             if test $altivec = "yes"; then
                 echo "WARNING: Tuning for PPC75x but AltiVec enabled!";
             fi
             TUNECPU=ppc750
         ;;
         G4|g4|745*|ppc745*|PowerPC745*)
-            add_cflags "-march=7450 -mpowerpc-gfxopt"
+            add_cflags "-mcpu=7450 -mpowerpc-gfxopt"
             if test $altivec = "no"; then
                 echo "WARNING: Tuning for PPC745x but AltiVec disabled!";
             fi
             TUNECPU=ppc7450
         ;;
         74*|ppc74*|PowerPC74*)
-            add_cflags "-march=7400 -mpowerpc-gfxopt"
+            add_cflags "-mcpu=7400 -mpowerpc-gfxopt"
             if test $altivec = "no"; then
                 echo "WARNING: Tuning for PPC74xx but AltiVec disabled!";
             fi
             TUNECPU=ppc7400
         ;;
         G5|g5|970|ppc970|PowerPC970|power4*|Power4*)
-            add_cflags "-march=970 -mpowerpc-gfxopt -mpowerpc64"
+            add_cflags "-mcpu=970 -mpowerpc-gfxopt -mpowerpc64"
             if test $altivec = "no"; then
                 echo "WARNING: Tuning for PPC970 but AltiVec disabled!";
             fi
@@ -1104,7 +1104,7 @@ if test $cpu != "generic"; then
             add_cflags "-march=$cpu"
         ;;
         sparc64)
-            add_cflags "-march=v9"
+            add_cflags "-mcpu=v9"
         ;;
         *)
         echo "WARNING: Unknown CPU \"$cpu\", ignored."