Fix:

error: implicit declaration of function 'panic' is invalid in C99

panic is the old name of this function. Its new name is Tcl_Panic. tcl.h
defines a compatibility macro but not on macOS because of an alleged
conflict with mach/mach.h.
--- generic/tkTableTag.c.orig	2013-04-18 18:59:59.000000000 -0500
+++ generic/tkTableTag.c	2020-10-06 01:22:54.000000000 -0500
@@ -212,7 +212,7 @@
     TableJoinTag *jtagPtr = (TableJoinTag *) tagPtr;
 
     if (jtagPtr->magic != 0x99ABCDEF) {
-	panic("bad mojo in TableResetTag");
+	Tcl_Panic("bad mojo in TableResetTag");
     }
 
     memset((VOID *) jtagPtr, 0, sizeof(TableJoinTag));
@@ -269,7 +269,7 @@
     unsigned int prio;
 
     if (jtagPtr->magic != 0x99ABCDEF) {
-	panic("bad mojo in TableMergeTag");
+	Tcl_Panic("bad mojo in TableMergeTag");
     }
 
 #ifndef NO_TAG_PRIORITIES
@@ -432,7 +432,7 @@
 	    if (bottom)	{ *bottom	= tagPtr->bd[3]; }
 	    break;
 	default:
-	    panic("invalid border value '%d'\n", tagPtr->borders);
+	    Tcl_Panic("invalid border value '%d'\n", tagPtr->borders);
 	    break;
     }
     return tagPtr->borders;
--- generic/tkTableUtil.c.orig	2013-04-18 18:59:59.000000000 -0500
+++ generic/tkTableUtil.c	2020-10-06 01:22:45.000000000 -0500
@@ -105,7 +105,7 @@
 	bordersPtr	= &(tagPtr->borders);
 	bdPtr		= tagPtr->bd;
     } else {
-	panic("invalid type given to TableOptionBdSet\n");
+	Tcl_Panic("invalid type given to TableOptionBdSet\n");
 	return TCL_ERROR; /* lint */
     }
 
@@ -188,7 +188,7 @@
     } else if (type == BD_TABLE_WIN) {
 	return ((TableEmbWindow *) widgRec)->borderStr;
     } else {
-	panic("invalid type given to TableOptionBdSet\n");
+	Tcl_Panic("invalid type given to TableOptionBdSet\n");
 	return NULL; /* lint */
     }
 }