gmp/mpfr: fix up dependencies to stop continous rebuild with --disable-shared

Don't list the shared objects as targets for the host compilation now that
we compile with --disable-shared.

package/gmp/gmp.mk

@@ -89,7 +89,7 @@ $(GMP_DIR2)/.configured: $(GMP_DIR)/.unpacked
 	)
 	touch $@
 
-$(GMP_HOST_DIR)/lib/libgmp$(HOST_LIBEXT) $(GMP_HOST_DIR)/lib/libgmp$(HOST_SHREXT) $(GMP_HOST_DIR)/lib/libgmp$(HOST_SHREXT).(GMP_LIBVERSION): $(GMP_DIR2)/.configured
+$(GMP_HOST_DIR)/lib/libgmp$(HOST_LIBEXT): $(GMP_DIR2)/.configured
 	$(MAKE) -C $(GMP_DIR2) install
 
 host-libgmp: $(GMP_HOST_DIR)/lib/$(GMP_HOST_BINARY)

package/mpfr/mpfr.mk

@@ -103,7 +103,7 @@ $(MPFR_DIR2)/.configured: $(MPFR_DIR)/.unpacked $(GMP_HOST_DIR)/lib/$(GMP_HOST_B
 	)
 	touch $@
 
-$(MPFR_HOST_DIR)/lib/libmpfr$(HOST_LIBEXT) $(MPFR_HOST_DIR)/lib/libmpfr$(HOST_SHREXT) $(MPFR_HOST_DIR)/lib/libmpfr$(HOST_SHREXT).$(MPFR_LIBVERSION): $(MPFR_DIR2)/.configured
+$(MPFR_HOST_DIR)/lib/libmpfr$(HOST_LIBEXT): $(MPFR_DIR2)/.configured
 	$(MAKE) -C $(MPFR_DIR2) install
 
 host-libmpfr: $(MPFR_HOST_DIR)/lib/$(MPFR_HOST_BINARY)