* Made it possible to dynamically check for supported linker options

  using the check_ld function.
* Only use --warn-unresolved-symbols with linkers that support it.

Rules.mak

@@ -114,6 +114,9 @@ check_gcc=$(shell \
 check_as=$(shell \
 	if $(CC) -Wa,$(1) -Wa,-Z -c -o /dev/null -xassembler /dev/null > /dev/null 2>&1; \
 	then echo "-Wa,$(1)"; fi)
+check_ld=$(shell \
+	if $(LD) $(1) -o /dev/null -b binary /dev/null > /dev/null 2>&1; \
+	then echo "$(1)"; fi)
 
 ARFLAGS:=cr
 

libpthread/linuxthreads.old_db/Makefile.in

@@ -8,7 +8,7 @@
 # Get the thread include dependencies and shared object name
 CFLAGS-linuxthreads.old_db := -DNOT_IN_libc -DLIBPTHREAD_SO="\"libpthread.so.$(MAJOR_VERSION)\""
 
-LDFLAGS-libthread_db.so := $(LDFLAGS_NOSTRIP) -s --warn-unresolved-symbols
+LDFLAGS-libthread_db.so := $(LDFLAGS_NOSTRIP) -s $(call check_ld,--warn-unresolved-symbols)
 
 LIBS-libthread_db.so := $(LIBS)
 

libpthread/linuxthreads_db/Makefile.in

@@ -8,7 +8,7 @@
 # Get the thread include dependencies and shared object name
 CFLAGS-linuxthreads_db := -DNOT_IN_libc -DLIBPTHREAD_SO="\"libpthread.so.$(MAJOR_VERSION)\""
 
-LDFLAGS-libthread_db.so := $(LDFLAGS_NOSTRIP) -s --warn-unresolved-symbols
+LDFLAGS-libthread_db.so := $(LDFLAGS_NOSTRIP) -s $(call check_ld,--warn-unresolved-symbols)
 
 LIBS-libthread_db.so := $(LIBS)