Make configure detect required libraries to link.

lib/Makefile

@@ -4,7 +4,6 @@ LIBXBPS_MAJOR = 0
 LIBXBPS_MINOR = 0
 LIBXBPS_MICRO = 0
 LIBXBPS_SHLIB = libxbps.so.$(LIBXBPS_MAJOR).$(LIBXBPS_MINOR).$(LIBXBPS_MICRO)
-LDFLAGS += -lpthread -larchive -lssl -lz
 LDFLAGS += -shared -Wl,-soname,libxbps.so.$(LIBXBPS_MAJOR)
 
 # portableproplib
@@ -19,7 +18,6 @@ LIBPROP_CFLAGS = -Wno-cast-qual -Wno-unused-parameter
 
 ifdef USE_EXTERNAL_PROPLIB
 LIBPROP_OBJS =
-LDFLAGS += -lprop
 endif
 
 # libfetch
@@ -33,7 +31,6 @@ LIBFETCH_GEN = fetch/ftperr.h fetch/httperr.h
 
 ifdef USE_EXTERNAL_LIBFETCH
 LIBFETCH_OBJS =
-LDFLAGS += -lfetch
 endif
 
 # libxbps