Fix BUILD.gn files and add presubmit step

test/fuzzer/fuzzer.gyp

Index: test/fuzzer/fuzzer.gyp
diff --git a/test/fuzzer/fuzzer.gyp b/test/fuzzer/fuzzer.gyp
index a28a9c957c9095b3213391793aa05ac92b3500cf..527389617eb98c74f88ac1f958c4d812a583c299 100644
--- a/test/fuzzer/fuzzer.gyp
+++ b/test/fuzzer/fuzzer.gyp
@@ -196,8 +196,8 @@
         'wasm-data-section.cc',
         '../common/wasm/wasm-module-runner.cc',
         '../common/wasm/wasm-module-runner.h',
-        '../fuzzer/wasm-section-fuzzers.cc',
-        '../fuzzer/wasm-section-fuzzers.h',
+        'wasm-section-fuzzers.cc',
+        'wasm-section-fuzzers.h',
       ],
     },
     {
@@ -226,8 +226,8 @@
         'wasm-function-sigs-section.cc',
         '../common/wasm/wasm-module-runner.cc',
         '../common/wasm/wasm-module-runner.h',
-        '../fuzzer/wasm-section-fuzzers.cc',
-        '../fuzzer/wasm-section-fuzzers.h',
+        'wasm-section-fuzzers.cc',
+        'wasm-section-fuzzers.h',
       ],
     },
     {
@@ -256,8 +256,8 @@
         'wasm-globals-section.cc',
         '../common/wasm/wasm-module-runner.cc',
         '../common/wasm/wasm-module-runner.h',
-        '../fuzzer/wasm-section-fuzzers.cc',
-        '../fuzzer/wasm-section-fuzzers.h',
+        'wasm-section-fuzzers.cc',
+        'wasm-section-fuzzers.h',
       ],
     },
     {
@@ -286,8 +286,8 @@
         'wasm-imports-section.cc',
         '../common/wasm/wasm-module-runner.cc',
         '../common/wasm/wasm-module-runner.h',
-        '../fuzzer/wasm-section-fuzzers.cc',
-        '../fuzzer/wasm-section-fuzzers.h',
+        'wasm-section-fuzzers.cc',
+        'wasm-section-fuzzers.h',
       ],
     },
     {
@@ -316,8 +316,8 @@
         'wasm-memory-section.cc',
         '../common/wasm/wasm-module-runner.cc',
         '../common/wasm/wasm-module-runner.h',
-        '../fuzzer/wasm-section-fuzzers.cc',
-        '../fuzzer/wasm-section-fuzzers.h',
+        'wasm-section-fuzzers.cc',
+        'wasm-section-fuzzers.h',
       ],
     },
     {
@@ -346,8 +346,8 @@
         'wasm-names-section.cc',
         '../common/wasm/wasm-module-runner.cc',
         '../common/wasm/wasm-module-runner.h',
-        '../fuzzer/wasm-section-fuzzers.cc',
-        '../fuzzer/wasm-section-fuzzers.h',
+        'wasm-section-fuzzers.cc',
+        'wasm-section-fuzzers.h',
       ],
     },
     {
@@ -376,8 +376,8 @@
         'wasm-types-section.cc',
         '../common/wasm/wasm-module-runner.cc',
         '../common/wasm/wasm-module-runner.h',
-        '../fuzzer/wasm-section-fuzzers.cc',
-        '../fuzzer/wasm-section-fuzzers.h',
+        'wasm-section-fuzzers.cc',
+        'wasm-section-fuzzers.h',
       ],
     },
     {