!890 [LIBC-TEST] Fix x86 libc-test build error

Merge pull request !890 from guzhihao4/fix_libctest_for_x86

libc-test/src/common/BUILD.gn

@@ -105,6 +105,7 @@ config("config_unittest") {
     "-Wno-error=unused-function",
     "-g",
     "-D_FILE_OFFSET_BITS=64",
+    "-Wno-constant-conversion",
   ]
 
   ldflags = [ "-nostdlib" ]

musl_src.gni

@@ -144,6 +144,7 @@ if (musl_arch == "arm") {
   musl_src_arch_file = [
     "src/fenv/x86_64/fenv.s",
     "src/ldso/x86_64/dlsym.s",
+    "src/ldso/x86_64/dlvsym.s",
     "src/ldso/x86_64/tlsdesc.s",
     "src/math/x86_64/__invtrigl.s",
     "src/math/x86_64/acosl.s",