Add pkg-config files for libpq and ecpg libraries

This will hopefully be easier to use than pg_config for users who are
already used to the pkg-config interface.  It also works better for
multi-arch installations.

reviewed by Tom Lane

src/interfaces/ecpg/compatlib/Makefile

@@ -32,6 +32,8 @@ LIBS := $(filter-out -lpgport, $(LIBS))
 
 OBJS= informix.o $(filter snprintf.o, $(LIBOBJS))
 
+PKG_CONFIG_REQUIRES_PRIVATE = libecpg libpgtypes
+
 all: all-lib
 
 .PHONY: submake-ecpglib submake-pgtypeslib

src/interfaces/ecpg/ecpglib/Makefile

@@ -43,6 +43,8 @@ ifeq ($(PORTNAME), win32)
 SHLIB_LINK += -lshfolder
 endif
 
+PKG_CONFIG_REQUIRES_PRIVATE = libpq libpgtypes
+
 all: all-lib
 
 .PHONY: submake-pgtypeslib