pkg-config Requires.private entries should be comma-separated

In the .pc (pkg-config) files generated by the make and meson builds,
the Requires.private entries use different delimiters.  The make build
uses spaces, the meson build uses commas. The pkg-config documentation
says that it should be comma-separated, but apparently about half the
.pc in the wild use just spaces.  The pkg-config source code
acknowledges that both commas and spaces work.

This changes the make build to use commas, for consistency.

Reviewed-by: Andres Freund <andres@anarazel.de>
Discussion: https://www.postgresql.org/message-id/flat/1fb52d61-0964-2d8e-87d9-e8be830e2b24%40enterprisedb.com

src/interfaces/ecpg/compatlib/Makefile

@@ -32,7 +32,7 @@ OBJS = \
 	$(WIN32RES) \
 	informix.o
 
-PKG_CONFIG_REQUIRES_PRIVATE = libecpg libpgtypes
+PKG_CONFIG_REQUIRES_PRIVATE = libecpg, libpgtypes
 
 all: all-lib
 

src/interfaces/ecpg/ecpglib/Makefile

@@ -41,7 +41,7 @@ SHLIB_PREREQS = submake-libpq submake-pgtypeslib
 
 SHLIB_EXPORTS = exports.txt
 
-PKG_CONFIG_REQUIRES_PRIVATE = libpq libpgtypes
+PKG_CONFIG_REQUIRES_PRIVATE = libpq, libpgtypes
 
 all: all-lib
 

src/interfaces/libpq/Makefile

@@ -96,7 +96,7 @@ SHLIB_PREREQS = submake-libpgport
 SHLIB_EXPORTS = exports.txt
 
 ifeq ($(with_ssl),openssl)
-PKG_CONFIG_REQUIRES_PRIVATE = libssl libcrypto
+PKG_CONFIG_REQUIRES_PRIVATE = libssl, libcrypto
 endif
 
 all: all-lib libpq-refs-stamp