Bug 1758741 - Allow ld path to be set as environment variable. r=mt

Submitted on behalf of Zi Lin, the author of the patch.

Differential Revision: https://phabricator.services.mozilla.com/D141119

coreconf/Linux.mk

@@ -6,6 +6,7 @@
 CC     ?= gcc
 CCC    ?= g++
 RANLIB ?= ranlib
+LD     ?= ld
 
 include $(CORE_DEPTH)/coreconf/UNIX.mk
 
@@ -157,8 +158,8 @@ DSO_LDOPTS		= -shared $(ARCHFLAG) -Wl,--gc-sections
 # Also, -z defs conflicts with Address Sanitizer, which emits relocations
 # against the libsanitizer runtime built into the main executable.
 ZDEFS_FLAG		= -Wl,-z,defs
-DSO_LDOPTS		+= $(if $(findstring 2.11.90.0.8,$(shell ld -v)),,$(ZDEFS_FLAG))
-LDFLAGS			+= $(ARCHFLAG) -z noexecstack
+DSO_LDOPTS     += $(if $(findstring 2.11.90.0.8,$(shell $(LD) -v)),,$(ZDEFS_FLAG))
+LDFLAGS		   += $(ARCHFLAG) -z noexecstack
 
 # On Maemo, we need to use the -rpath-link flag for even the standard system
 # library directories.