use a more conventional way to generate and include the lmpinstalledpkgs.h file

src/Makefile

@@ -153,10 +153,13 @@ help:
 
 lmpinstalledpkgs.h: $(SRC) $(INC)
 	@echo 'Gathering installed package information (may take a little while)'
-	@echo 'const char * LAMMPS_NS::LAMMPS::installed_packages[] = {' > lmpinstalledpkgs.tmp
+	@echo '#ifndef LMP_INSTALLED_PKGS' >  lmpinstalledpkgs.tmp
+	@echo '#define LMP_INSTALLED_PKGS' >> lmpinstalledpkgs.tmp
+	@echo 'const char * LAMMPS_NS::LAMMPS::installed_packages[] = {' >> lmpinstalledpkgs.tmp
 	@for p in $(PACKAGEUC) $(PACKUSERUC); do info=$$($(SHELL) Package.sh $$p installed); \
              [ -n "$$info" ] && echo "\"$$info\"" | sed -e 's/".*package \(.*\)"/"\1",/' >> lmpinstalledpkgs.tmp || :; done
 	@echo ' NULL };' >> lmpinstalledpkgs.tmp
+	@echo '#endif' >> lmpinstalledpkgs.tmp
 	@if [ -f lmpinstalledpkgs.h ]; \
           then test "`diff --brief lmpinstalledpkgs.tmp lmpinstalledpkgs.h`" != "" && \
 	        mv lmpinstalledpkgs.tmp lmpinstalledpkgs.h || rm lmpinstalledpkgs.tmp ; \

src/lammps.cpp

@@ -51,6 +51,8 @@
 #include "version.h"
 #include "error.h"
 
+#include "lmpinstalledpkgs.h"
+
 using namespace LAMMPS_NS;
 
 static void print_style(FILE *fp, const char *str, int &pos);
@@ -978,8 +980,6 @@ void print_style(FILE *fp, const char *str, int &pos)
   }
 }
 
-#include "lmpinstalledpkgs.h"
-
 void LAMMPS::print_config(FILE *fp)
 {
   const char *pkg;