icd: stop generating icd-dispatch-entrypoints.c

Let ICDs define XGL entrypoints directly.  This requires the Intel ICD to
rename intelSomeEntryPoint() to xglSomeEntryPoint().  In addition, the ICD
needs to be linked with -Bsymbolic to make symbol resolving work for
xglGetProcAddr().

v2: use -Bsymbolic-functions
diff --git a/icd/intel/cmd_mi.c b/icd/intel/cmd_mi.c
index 6cd63a0..66345d0 100644
--- a/icd/intel/cmd_mi.c
+++ b/icd/intel/cmd_mi.c
@@ -119,7 +119,7 @@
     }
 }
 
-XGL_VOID XGLAPI intelCmdBeginQuery(
+ICD_EXPORT XGL_VOID XGLAPI xglCmdBeginQuery(
     XGL_CMD_BUFFER                              cmdBuffer,
     XGL_QUERY_POOL                              queryPool,
     XGL_UINT                                    slot,
@@ -143,7 +143,7 @@
     }
 }
 
-XGL_VOID XGLAPI intelCmdEndQuery(
+ICD_EXPORT XGL_VOID XGLAPI xglCmdEndQuery(
     XGL_CMD_BUFFER                              cmdBuffer,
     XGL_QUERY_POOL                              queryPool,
     XGL_UINT                                    slot)
@@ -167,7 +167,7 @@
     }
 }
 
-XGL_VOID XGLAPI intelCmdResetQueryPool(
+ICD_EXPORT XGL_VOID XGLAPI xglCmdResetQueryPool(
     XGL_CMD_BUFFER                              cmdBuffer,
     XGL_QUERY_POOL                              queryPool,
     XGL_UINT                                    startQuery,
@@ -176,7 +176,7 @@
     /* no-op */
 }
 
-XGL_VOID XGLAPI intelCmdSetEvent(
+ICD_EXPORT XGL_VOID XGLAPI xglCmdSetEvent(
     XGL_CMD_BUFFER                              cmdBuffer,
     XGL_EVENT                                   event_)
 {
@@ -186,7 +186,7 @@
     cmd_batch_immediate(cmd, event->obj.mem->bo, 0, 1);
 }
 
-XGL_VOID XGLAPI intelCmdResetEvent(
+ICD_EXPORT XGL_VOID XGLAPI xglCmdResetEvent(
     XGL_CMD_BUFFER                              cmdBuffer,
     XGL_EVENT                                   event_)
 {
@@ -196,7 +196,7 @@
     cmd_batch_immediate(cmd, event->obj.mem->bo, 0, 0);
 }
 
-XGL_VOID XGLAPI intelCmdWriteTimestamp(
+ICD_EXPORT XGL_VOID XGLAPI xglCmdWriteTimestamp(
     XGL_CMD_BUFFER                              cmdBuffer,
     XGL_TIMESTAMP_TYPE                          timestampType,
     XGL_GPU_MEMORY                              destMem,