test: set a 1.2G max_rss for test-libc test cases

1G was the highest value I observed for any test case on x86_64-linux. This
change should prevent OOM conditions in CI.

Author: alexrp

build.zig

@@ -609,6 +609,8 @@ pub fn build(b: *std.Build) !void {
         .optimize_modes = optimization_modes,
         .test_filters = test_filters,
         .test_target_filters = test_target_filters,
+        // Highest RSS observed in any test case was exactly 1G on x86_64-linux.
+        .max_rss = 1288490188,
     })) |test_libc_step| test_step.dependOn(test_libc_step);
 }
 

test/src/Libc.zig

@@ -10,6 +10,7 @@ pub const Options = struct {
     optimize_modes: []const std.builtin.OptimizeMode,
     test_filters: []const []const u8,
     test_target_filters: []const []const u8,
+    max_rss: usize,
 };
 
 const TestCase = struct {
@@ -100,6 +101,7 @@ pub fn addTarget(libc: *const Libc, target: std.Build.ResolvedTarget) void {
             const exe = libc.b.addExecutable(.{
                 .name = test_case.name,
                 .root_module = mod,
+                .max_rss = libc.options.max_rss,
             });
 
             const run = libc.b.addRunArtifact(exe);
@@ -108,6 +110,7 @@ pub fn addTarget(libc: *const Libc, target: std.Build.ResolvedTarget) void {
             run.expectStdErrEqual("");
             run.expectStdOutEqual("");
             run.expectExitCode(0);
+            run.step.max_rss = libc.options.max_rss;
 
             libc.root_step.dependOn(&run.step);
         }