configure: fix inline asm checks

Commit 8c893aa3 removed quotes that were required to detect
inline asm:

check_insn armv5te qadd r0, r0, r0
.../test.c:1:34: error: expected string literal in 'asm'
void foo(void){ __asm__ volatile(qadd r0, r0, r0); }

The correct code is:

void foo(void){ __asm__ volatile("qadd r0, r0, r0"); }

Commit message written by Frank Liberato <liberato@chromium.org>
Signed-off-by: Martin Storsjö <martin@martin.st>

configure

@@ -866,7 +866,7 @@ EOF
 
 check_insn(){
     log check_insn "$@"
-    check_inline_asm ${1}_inline "$2"
+    check_inline_asm ${1}_inline "\"$2\""
     check_as ${1}_external "$2"
 }