aix: Remove checks for very old OS versions

Reviewed-By: Thomas Munro <thomas.munro@gmail.com>
Discussion: https://postgr.es/m/20220807012914.ydz73yte6j3coulo@awork3.anarazel.de

src/backend/Makefile

@@ -101,15 +101,7 @@ postgres: $(POSTGRES_IMP)
 
 $(POSTGRES_IMP): $(OBJS)
 	$(LD) $(LDREL) $(LDOUT) SUBSYS.o $(call expand_subsys,$^)
-ifeq ($(host_os), aix3.2.5)
 	$(MKLDEXPORT) SUBSYS.o $(bindir)/postgres > $@
-else
-ifneq (,$(findstring aix4.1, $(host_os)))
-	$(MKLDEXPORT) SUBSYS.o $(bindir)/postgres > $@
-else
-	$(MKLDEXPORT) SUBSYS.o . > $@
-endif
-endif
 	@rm -f SUBSYS.o
 
 endif # aix

src/makefiles/Makefile.aix

@@ -8,19 +8,9 @@ AROPT = crs
 # -blibpath must contain ALL directories where we should look for libraries
 libpath := $(shell echo $(subst -L,:,$(filter -L/%,$(LDFLAGS))) | sed -e's/ //g'):/usr/lib:/lib
 
-ifeq ($(host_os), aix3.2.5)
-	rpath = -L'$(rpathdir)'
-else
-	rpath = -Wl,-blibpath:'$(rpathdir)$(libpath)'
-endif
+rpath = -Wl,-blibpath:'$(rpathdir)$(libpath)'
 
-ifeq ($(host_os), aix3.2.5)
-ifneq ($(GCC), yes)
-	LDFLAGS_SL += -e _nostart -H512 -bM:SRE
-endif
-else
-	LDFLAGS_SL += -Wl,-bnoentry -Wl,-H512 -Wl,-bM:SRE
-endif
+LDFLAGS_SL += -Wl,-bnoentry -Wl,-H512 -Wl,-bM:SRE
 
 # env var name to use in place of LD_LIBRARY_PATH
 ld_library_path_var = LIBPATH

src/template/aix

@@ -6,9 +6,6 @@
 # non-default CFLAGS setting.
 if test "$GCC" != yes ; then
   case $host_os in
-    aix3.2.5 | aix4.1*)
-      CFLAGS="-O -qmaxmem=16384"
-      ;;
     *)
       CFLAGS="-O2 -qmaxmem=16384"
       ;;