Set shared library path for in-tree TAP tests

When the TAP tests are run in-tree (make check), set the shared library
path using the appropriate environment variable, using a logic similar
to pg_regress, so that the right libraries are used.

src/Makefile.global.in

@@ -300,6 +300,16 @@ PROVE = @PROVE@
 PG_PROVE_FLAGS = --ext='.pl' -I $(top_srcdir)/src/test/perl/
 PROVE_FLAGS = --verbose
 
+# prepend to path if already set, else just set it
+define add_to_path
+$(1)='$(if $($(1)),$(2):$$$(1),$(2))'
+endef
+
+# platform-specific environment variable to set shared library path
+define ld_library_path_var
+$(if $(filter $(PORTNAME),darwin),DYLD_LIBRARY_PATH,$(if $(filter $(PORTNAME),aix),LIBPATH,LD_LIBRARY_PATH))
+endef
+
 define prove_installcheck
 cd $(srcdir) && TESTDIR='$(CURDIR)' PATH="$(bindir):$$PATH" PGPORT='6$(DEF_PGPORT)' $(PROVE) $(PG_PROVE_FLAGS) $(PROVE_FLAGS)
 endef
@@ -307,7 +317,7 @@ endef
 define prove_check
 $(MKDIR_P) tmp_check/log
 $(MAKE) -C $(top_builddir) DESTDIR=$(CURDIR)/tmp_check/install install >$(CURDIR)/tmp_check/log/install.log 2>&1
-cd $(srcdir) && TESTDIR='$(CURDIR)' PATH="$(CURDIR)/tmp_check/install$(bindir):$$PATH" PGPORT='6$(DEF_PGPORT)' $(PROVE) $(PG_PROVE_FLAGS) $(PROVE_FLAGS)
+cd $(srcdir) && TESTDIR='$(CURDIR)' PATH="$(CURDIR)/tmp_check/install$(bindir):$$PATH" $(call add_to_path,$(ld_library_path_var),$(CURDIR)/tmp_check/install$(libdir)) PGPORT='6$(DEF_PGPORT)' $(PROVE) $(PG_PROVE_FLAGS) $(PROVE_FLAGS)
 endef
 
 # Installation.