dthelp: Resolve GCC 10 errors about multiple definitions of global variables

cde/programs/dthelp/parser/canon1/parser/Imakefile

@@ -44,6 +44,7 @@ XLATEOBJECTS = $(HELPTAGSRC)/LocaleXlate.o $(HELPTAGSRC)/XlationSvc.o
 APPLOBJECTS = \
 	$(HELPTAGSRC)/custom.o \
 	$(HELPTAGSRC)/default.o \
+	$(HELPTAGSRC)/global.o \
 	$(HELPTAGSRC)/help.o \
 	$(HELPTAGSRC)/make.o \
 	$(HELPTAGSRC)/option.o \

cde/programs/dthelp/parser/canon1/parser/parser.c

@@ -35,6 +35,8 @@
 #include "if.h"
 #include "entext.h"
 
+char *user_defined_entities M_PARINIT("USER-DEFINED-ENTITIES");
+
 static void scanloop(LOGICAL prolog);
 
 /* Main procedure */

cde/programs/dthelp/parser/canon1/parser/parser.h

@@ -301,7 +301,7 @@ M_PAREXTERN int m_prevcon ;
 M_PAREXTERN int m_token ;
 M_PAREXTERN int m_scanval ;
 
-char *user_defined_entities M_PARINIT("USER-DEFINED-ENTITIES");
+extern char *user_defined_entities;
 
 /* Declarations for tentative list of omitted tags when checking for tag
    MINimization */