[gcc r13-4264] d: respect --enable-link-mutex configure option

[Martin Liska <marxin@gcc.gnu.org>]

https://gcc.gnu.org/g:52a0ef696e1d7858fde1ded81ac8063a5768127c

commit r13-4264-g52a0ef696e1d7858fde1ded81ac8063a5768127c
Author: Martin Liska <mliska@suse.cz>
Date:   Tue Nov 22 10:39:50 2022 +0100

    d: respect --enable-link-mutex configure option
    
    I noticed the option is ignored because @DO_LINK_MUTEX@
    is not defined in d/Make-lang.in.
    
    gcc/ChangeLog:
    
            * Makefile.in: Set DO_LINK_MUTEX.
    
    gcc/d/ChangeLog:
    
            * Make-lang.in: Use it as $DO_LINK_MUTEX.

Diff:
---
 gcc/Makefile.in    | 1 +
 gcc/d/Make-lang.in | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/gcc/Makefile.in b/gcc/Makefile.in
index 5ad638f59d8..c57d62229ee 100644
--- a/gcc/Makefile.in
+++ b/gcc/Makefile.in
@@ -272,6 +272,7 @@ COMPILER += $(CET_HOST_FLAGS)
 
 NO_PIE_CFLAGS = @NO_PIE_CFLAGS@
 NO_PIE_FLAG = @NO_PIE_FLAG@
+DO_LINK_MUTEX = @DO_LINK_MUTEX@
 
 # We don't want to compile the compilers with -fPIE, it make PCH fail.
 COMPILER += $(NO_PIE_CFLAGS)
diff --git a/gcc/d/Make-lang.in b/gcc/d/Make-lang.in
index 6f9b2e5c26a..984b1d63dcb 100644
--- a/gcc/d/Make-lang.in
+++ b/gcc/d/Make-lang.in
@@ -70,7 +70,7 @@ DPOSTCOMPILE = @mv $(@D)/$(DEPDIR)/$(*F).TPo $(@D)/$(DEPDIR)/$(*F).Po
 DLINKER = $(GDC) $(NO_PIE_FLAG) -lstdc++
 
 # Like LINKER, but use a mutex for serializing front end links.
-ifeq (@DO_LINK_MUTEX@,true)
+ifeq ($(DO_LINK_MUTEX),true)
 DLLINKER = $(SHELL) $(srcdir)/lock-and-run.sh linkfe.lck $(DLINKER)
 else
 DLLINKER = $(DLINKER)