Merge pull request #1558 from Kangz/fix_build_gn

BUILD.gn: remove reference to non-existent header
diff --git a/BUILD.gn b/BUILD.gn
index a84dbe2..5d5b150 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -58,7 +58,6 @@
     "SPIRV/SpvBuilder.cpp",
     "SPIRV/SpvBuilder.h",
     "SPIRV/SpvPostProcess.cpp",
-    "SPIRV/SpvPostProcess.h",
     "SPIRV/bitutils.h",
     "SPIRV/disassemble.cpp",
     "SPIRV/disassemble.h",