configure: check for --as-needed support early

This moves the check for --as-needed linker support before all
library tests, ensuring consistent behaviour between the checks
and the actual link step.
Signed-off-by: Mans Rullgard <mans@mansr.com>

configure

@@ -2722,6 +2722,8 @@ if enabled asm; then
         $nogas "GNU assembler not found, install gas-preprocessor"
 fi
 
+check_ldflags -Wl,--as-needed
+
 if check_func dlopen; then
     ldl=
 elif check_func dlopen -ldl; then
@@ -2951,7 +2953,6 @@ enabled extra_warnings && check_cflags -Winline
 
 # add some linker flags
 check_ldflags -Wl,--warn-common
-check_ldflags -Wl,--as-needed
 check_ldflags '-Wl,-rpath-link,\$(BUILD_ROOT)/libpostproc -Wl,-rpath-link,\$(BUILD_ROOT)/libswscale -Wl,-rpath-link,\$(BUILD_ROOT)/libavfilter -Wl,-rpath-link,\$(BUILD_ROOT)/libavdevice -Wl,-rpath-link,\$(BUILD_ROOT)/libavformat -Wl,-rpath-link,\$(BUILD_ROOT)/libavcodec -Wl,-rpath-link,\$(BUILD_ROOT)/libavutil'
 test_ldflags -Wl,-Bsymbolic && append SHFLAGS -Wl,-Bsymbolic