configure: detect Open64 compiler

Originally committed as revision 25135 to svn://svn.ffmpeg.org/ffmpeg/trunk

configure

@@ -1975,6 +1975,14 @@ elif $cc -v 2>&1 | grep -q 'PathScale\|Path64'; then
     AS_DEPFLAGS='-MMD -MF $(@:.o=.d) -MT $@'
     speed_cflags='-O2'
     size_cflags='-Os'
+elif $cc -v 2>&1 | grep -q Open64; then
+    cc_type=open64
+    cc_version=__OPEN64__
+    cc_ident=$($cc -v 2>&1 | head -n1 | tr -d :)
+    CC_DEPFLAGS='-MMD -MF $(@:.o=.d) -MT $@'
+    AS_DEPFLAGS='-MMD -MF $(@:.o=.d) -MT $@'
+    speed_cflags='-O2'
+    size_cflags='-Os'
 fi
 
 test -n "$cc_type" && enable $cc_type ||