contrib/libunbound.pc.in: Embed the correct crypto dependencies

This commit removes the hardcoded dependency in the libunbound
pkg-config .pc file on the libcrypto and libssl modules and instead
populates the .pc file based on which crypto library was selected at
configure time.

Note that the .pc file specifies pkg-config module names for the
"Requires" line and this can vary from the library filename (e.g. "nss"
is the pkg-config module name vs. "nss3" being the library name).

configure.ac

@@ -761,6 +761,8 @@ AC_ARG_WITH([nss], AC_HELP_STRING([--with-nss=path],
 	fi
         LIBS="$LIBS -lnss3 -lnspr4"
 	SSLLIB=""
+	PC_CRYPTO_DEPENDENCY="nss nspr"
+	AC_SUBST(PC_CRYPTO_DEPENDENCY)
 	]
 )
 
@@ -781,6 +783,8 @@ AC_ARG_WITH([nettle], AC_HELP_STRING([--with-nettle=path],
 	fi
         LIBS="$LIBS -lhogweed -lnettle -lgmp"
 	SSLLIB=""
+	PC_CRYPTO_DEPENDENCY="hogweed nettle"
+	AC_SUBST(PC_CRYPTO_DEPENDENCY)
 	]
 )
 
@@ -790,6 +794,9 @@ ACX_WITH_SSL
 ACX_LIB_SSL
 SSLLIB="-lssl"
 
+PC_CRYPTO_DEPENDENCY="libcrypto libssl"
+AC_SUBST(PC_CRYPTO_DEPENDENCY)
+
 # check if -lcrypt32 is needed because CAPIENG needs that. (on windows)
 BAKLIBS="$LIBS"
 LIBS="-lssl $LIBS"

contrib/libunbound.pc.in

@@ -7,7 +7,7 @@ Name: unbound
 Description: Library with validating, recursive, and caching DNS resolver
 URL: http://www.unbound.net
 Version: @PACKAGE_VERSION@
-Requires: libcrypto libssl @PC_LIBEVENT_DEPENDENCY@
+Requires: @PC_CRYPTO_DEPENDENCY@ @PC_LIBEVENT_DEPENDENCY@
 Requires.private: @PC_PY_DEPENDENCY@
 Libs: -L${libdir} -lunbound
 Libs.private: @SSLLIB@ @LIBS@