fix bug for arm cross build

@@ -403,7 +403,13 @@ if [ $SRS_GPERF = YES ]; then LibGperfRoot="${SRS_OBJS}/gperf/include"; LibGperf
 # the link options, always use static link
 SrsLinkOptions=""; 
 if [ $SRS_SSL = YES ]; then if [ $SRS_USE_SYS_SSL = YES ]; then SrsLinkOptions="-lssl"; fi fi
-if [ $SRS_STATIC = YES ]; then SrsLinkOptions="${SrsLinkOptions} -static"; else SrsLinkOptions="${SrsLinkOptions} -ldl"; fi
+if [ $SRS_ARM_UBUNTU12 = YES ]; then 
+    # for arm cross build tool chain, always use static and ldl.
+    SrsLinkOptions="${SrsLinkOptions} -static -ldl"; 
+else
+    # for x86/64/arm directly build, use static or ldl.
+    if [ $SRS_STATIC = YES ]; then SrsLinkOptions="${SrsLinkOptions} -static"; else SrsLinkOptions="${SrsLinkOptions} -ldl"; fi
+fi
 
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 # Modules, compile each module, then link to binary