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/format.c b/icd/intel/format.c
index ab19eff..14aed74 100644
--- a/icd/intel/format.c
+++ b/icd/intel/format.c
@@ -531,7 +531,7 @@
     }
 }
 
-XGL_RESULT XGLAPI intelGetFormatInfo(
+ICD_EXPORT XGL_RESULT XGLAPI xglGetFormatInfo(
     XGL_DEVICE                                  device,
     XGL_FORMAT                                  format,
     XGL_FORMAT_INFO_TYPE                        infoType,