Let pkg-config determine botan dependency libs

Signed-off-by: Ruben Kerkhof <ruben@rubenkerkhof.com>
(cherry picked from commit 4adc8c71051a86d134439f94d300eac16051e158)

Author: rubenk

pdns/Makefile.am

@@ -74,12 +74,12 @@ pdns_server_LDADD= $(POLARSSL_LIBS) $(BOOST_SERIALIZATION_LIBS) $(LUA_LIBS) $(SQ
 
 if BOTAN110
 pdns_server_SOURCES += botan110signers.cc botansigners.cc
-pdns_server_LDADD += $(BOTAN110_LIBS) -lgmp -lrt
+pdns_server_LDADD += $(BOTAN110_LIBS)
 endif
 
 if BOTAN18
 pdns_server_SOURCES += botan18signers.cc botansigners.cc
-pdns_server_LDADD += $(BOTAN18_LIBS) -lgmp
+pdns_server_LDADD += $(BOTAN18_LIBS)
 endif
 
 if CRYPTOPP
@@ -161,12 +161,12 @@ endif
 
 if BOTAN110
 pdnssec_SOURCES += botan110signers.cc botansigners.cc
-pdnssec_LDADD += $(BOTAN110_LIBS) -lgmp -lrt
+pdnssec_LDADD += $(BOTAN110_LIBS)
 endif
 
 if BOTAN18
 pdnssec_SOURCES += botan18signers.cc botansigners.cc
-pdnssec_LDADD += $(BOTAN18_LIBS) -lgmp
+pdnssec_LDADD += $(BOTAN18_LIBS)
 endif
 
 if CRYPTOPP