configure: fix symver detection with icc 10

Apparently the compiler sometimes bypasses the normal assembler, in
which case the asm label variant works.  If the file contains any
inline asm, this bypassing is not done, and the assembler chokes on
invalid syntax.  Inserting a dummy asm() statement in the test when
the compiler supports it makes sure no shortcuts are taken and the
test fails as it should.

backport r23616 by mru


Originally committed as revision 23618 to svn://svn.ffmpeg.org/ffmpeg/branches/0.6

configure

@@ -253,6 +253,8 @@ EOF
   exit 0
 }
 
+quotes='""'
+
 log(){
     echo "$@" >> $logfile
 }
@@ -2741,7 +2743,7 @@ if test_ldflags -Wl,--version-script,$TMPV; then
     append SHFLAGS '-Wl,--version-script,\$(SUBDIR)lib\$(NAME).ver'
     check_cc <<EOF && enable symver_asm_label
 void ff_foo(void) __asm__ ("av_foo@VERSION");
-void ff_foo(void) {}
+void ff_foo(void) { ${inline_asm+__asm__($quotes);} }
 EOF
     check_cc <<EOF && enable symver_gnu_asm
 __asm__(".symver ff_foo,av_foo@VERSION");