[gcc r10-5996] Work around array out of bounds warning in mkdeps

[Andreas Krebbel]

https://gcc.gnu.org/g:3b5757ea87ad2274b841340335bf7536204e615b

commit r10-5996-g3b5757ea87ad2274b841340335bf7536204e615b
Author: Andreas Krebbel <krebbel@linux.ibm.com>
Date:   Thu Jan 16 10:41:44 2020 +0100

    Work around array out of bounds warning in mkdeps
    
    This suppresses an array out of bounds warning in mkdeps.c as proposed
    by Martin Sebor in the bugzilla.
    
    array subscript 2 is outside array bounds of ‘const char [2]’
    
    Since this warning does occur during bootstrap it currently breaks
    werror builds on IBM Z.
    
    The problem can be reproduced also on x86_64 by changing the inlining
    threshold using: --param max-inline-insns-auto=80
    
    Bootstrapped and regression tested on x86_64 and IBM Z.
    
    libcpp/ChangeLog:
    
    2020-01-16  Andreas Krebbel  <krebbel@linux.ibm.com>
    
    	PR tree-optimization/92176
    	* mkdeps.c (deps_add_default_target): Avoid calling apply_vpath to
    	suppress an array out of bounds warning.

Diff:
---
 libcpp/mkdeps.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libcpp/mkdeps.c b/libcpp/mkdeps.c
index 6b2575a..09a111f 100644
--- a/libcpp/mkdeps.c
+++ b/libcpp/mkdeps.c
@@ -268,7 +268,7 @@ deps_add_default_target (class mkdeps *d, const char *tgt)
     return;
 
   if (tgt[0] == '\0')
-    deps_add_target (d, "-", 1);
+    d->targets.push (xstrdup ("-"));
   else
     {
 #ifndef TARGET_OBJECT_SUFFIX