Fix fx_basic_memmgr_unittest.cpp under stricter GN rules

This caused a revert of the PDFium roll.

TBR=thestig@chromium.org

Review URL: https://codereview.chromium.org/1165863003

core/src/fxcrt/fx_basic_memmgr_unittest.cpp

diff --git a/core/src/fxcrt/fx_basic_memmgr_unittest.cpp b/core/src/fxcrt/fx_basic_memmgr_unittest.cpp
index c70f3b1..94e26c8 100644
--- a/core/src/fxcrt/fx_basic_memmgr_unittest.cpp
+++ b/core/src/fxcrt/fx_basic_memmgr_unittest.cpp
@@ -20,26 +20,27 @@
 // TODO(tsepez): re-enable OOM tests if we can find a way to
 // prevent it from hosing the bots.
 TEST(fxcrt, DISABLED_FX_AllocOOM) {
-    EXPECT_DEATH_IF_SUPPORTED(FX_Alloc(int, kMaxIntAlloc), "");
+    EXPECT_DEATH_IF_SUPPORTED((void) FX_Alloc(int, kMaxIntAlloc), "");
 
     int* ptr = FX_Alloc(int, 1);
     EXPECT_TRUE(ptr);
-    EXPECT_DEATH_IF_SUPPORTED(FX_Realloc(int, ptr, kMaxIntAlloc), "");
+    EXPECT_DEATH_IF_SUPPORTED((void) FX_Realloc(int, ptr, kMaxIntAlloc), "");
     FX_Free(ptr);
 }
 
 TEST(fxcrt, FX_AllocOverflow) {
-    EXPECT_DEATH_IF_SUPPORTED(FX_Alloc(int, kOverflowIntAlloc), "");
+    EXPECT_DEATH_IF_SUPPORTED((void) FX_Alloc(int, kOverflowIntAlloc), "");
 
     int* ptr = FX_Alloc(int, 1);
     EXPECT_TRUE(ptr);
-    EXPECT_DEATH_IF_SUPPORTED(FX_Realloc(int, ptr, kOverflowIntAlloc), "");
+    EXPECT_DEATH_IF_SUPPORTED(
+        (void) FX_Realloc(int, ptr, kOverflowIntAlloc), "");
     FX_Free(ptr);
 }
 
 TEST(fxcrt, FX_AllocOverflow2D) {
     EXPECT_DEATH_IF_SUPPORTED(
-        FX_Alloc2D(int, kWidth, kOverflowIntAlloc2D), "");
+        (void) FX_Alloc2D(int, kWidth, kOverflowIntAlloc2D), "");
 }
 
 TEST(fxcrt, DISABLED_FX_TryAllocOOM) {