perf pmu-events: Fix testing with JEVENTS_ARCH=all

The #slots literal will return NAN when not on ARM64 which causes a
perf test failure when not on an ARM64 for a JEVENTS_ARCH=all build:
..
 10.4: Parsing of PMU event table metrics with fake PMUs             : FAILED!
..
Add an is_test boolean so that the failure can be avoided when running
as a test.

Fixes: acef233 ("perf pmu: Add #slots literal support for arm64")
Signed-off-by: Ian Rogers <irogers@google.com>

Author: captain5050

tools/perf/tests/pmu-events.c

@@ -950,6 +950,7 @@ static int metric_parse_fake(const char *metric_name, const char *str)
 		pr_debug("expr__ctx_new failed");
 		return TEST_FAIL;
 	}
+	ctx->sctx.is_test = true;
 	if (expr__find_ids(str, NULL, ctx) < 0) {
 		pr_err("expr__find_ids failed\n");
 		return -1;

tools/perf/util/expr.h

@@ -9,6 +9,7 @@ struct expr_scanner_ctx {
 	char *user_requested_cpu_list;
 	int runtime;
 	bool system_wide;
+	bool is_test;
 };
 
 struct expr_parse_ctx {

tools/perf/util/expr.l

@@ -84,9 +84,11 @@ static int literal(yyscan_t scanner, const struct expr_scanner_ctx *sctx)
 	YYSTYPE *yylval = expr_get_lval(scanner);
 
 	yylval->num = expr__get_literal(expr_get_text(scanner), sctx);
-	if (isnan(yylval->num))
-		return EXPR_ERROR;
-
+	if (isnan(yylval->num)) {
+		if (!sctx->is_test)
+			return EXPR_ERROR;
+		yylval->num = 1;
+	}
 	return LITERAL;
 }
 %}