mac: minor tweaks to gcapi_mac target.

No behavior change.

The 11 SDK linker warns that building for both 10.6 and 10.7 is
deprecated and we build with -fatal_warnings, to that's a build error.

Ideally we get a flag to disable this warning. Else we could not pass
-fatal_warnings for this target and have a linker wrapper again to
filter out the warning ( :/ ), or we could bump up the deployment
target (which after this change requires changing only a single
number instead of 2). But that's for a future CL.

Bug: 1098738
Change-Id: I7952345f1333be023fab997cbf81baf394dfcc40
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2264592
Auto-Submit: Nico Weber <thakis@chromium.org>
Commit-Queue: Mark Mentovai <mark@chromium.org>
Reviewed-by: Mark Mentovai <mark@chromium.org>
Cr-Commit-Position: refs/heads/master@{#781913}

chrome/installer/gcapi_mac/BUILD.gn

@@ -7,15 +7,20 @@ import("//build/config/sysroot.gni")
 assert(is_mac)
 
 config("gcapi_config") {
+  # gcapi can be bundled with installers of other software, which might run
+  # on older macOS versions than chrome itself. To not making a dependency on
+  # gcapi a problem for these installers, make it target a very old version
+  # of macOS.
+  min_version = "10.6"
   cflags = [
     "-isysroot",
     rebase_path(sysroot, root_build_dir),
-    "-mmacosx-version-min=10.6",
+    "-mmacosx-version-min=$min_version",
   ]
   ldflags = [
     "-isysroot",
     rebase_path(sysroot, root_build_dir),
-    "-mmacosx-version-min=10.6",
+    "-mmacosx-version-min=$min_version",
   ]
 }
 
@@ -47,7 +52,7 @@ executable("gcapi_example") {
 
   # Every executable by default links to a hermetic libc++, so that we can
   # guarantee the capability of the standard library. Neither gcapi_lib
-  # not gcapi_example contain any significant use of the standard library
+  # nor gcapi_example contain any significant use of the standard library
   # and gcapi_lib is supposed to be redistributable to partners who don't
   # want to link our hermetic libc++, so set no_default_deps to not link to
   # our hermetic libc++.