Add and rearrange building of libraries

There's a need for a target that will build all of libcrypto, so let's
add 'build_libcrypto' that does this.  For ortogonality, let's also
add 'build_libssl'.  Have both also depend on 'libcrypto.pc' and
'libssl.pc' so those get built together with the libraries.
This makes 'all' depend on fewer things directly.
Reviewed-by: NTim Hudson <tjh@openssl.org>

Makefile.org

@@ -187,7 +187,7 @@ INSTALLDIRS=	\
 		$(INSTALL_PREFIX)$(OPENSSLDIR)/certs \
 		$(INSTALL_PREFIX)$(OPENSSLDIR)/private
 
-all: Makefile build_all openssl.pc libssl.pc libcrypto.pc
+all: Makefile build_all
 
 # as we stick to -e, CLEARENV ensures that local variables in lower
 # Makefiles remain local and variable. $${VAR+VAR} is tribute to Korn
@@ -272,7 +272,10 @@ sub_all: build_all
 
 build_all: build_libs build_apps build_tests build_tools
 
-build_libs: build_crypto build_ssl build_engines
+build_libs: build_libcrypto build_libssl openssl.pc
+
+build_libcrypto: build_crypto build_engines libcrypto.pc
+build_libssl: build_ssl libssl.pc
 
 build_crypto:
 	@dir=crypto; target=all; $(BUILD_ONE_CMD)