Add Windows file version information to libpq/test programs.

Back-patch to v15, the first version to install these programs.

Discussion: https://postgr.es/m/20220501080706.GA1542365@rfd.leadboat.com

Author: nmisch

src/interfaces/libpq/test/Makefile

@@ -1,5 +1,8 @@
 # src/interfaces/libpq/test/Makefile
 
+PGFILEDESC = "libpq test program"
+PGAPPICON = win32
+
 subdir = src/interfaces/libpq/test
 top_builddir = ../../../..
 include $(top_builddir)/src/Makefile.global
@@ -15,5 +18,7 @@ PROGS = libpq_testclient libpq_uri_regress
 
 all: $(PROGS)
 
+$(PROGS): $(WIN32RES)
+
 clean distclean maintainer-clean:
 	rm -f $(PROGS) *.o