Remove includes of windows tchar.h.

tchar.h introduces a bit of trickery on windows to map types like
_TCHAR and functions like _tcsrev() onto different underlying
implemenentations.  PDFium does not appear to use any of these.

Change-Id: Ic56dbbd47a39af71eb4108e13b70ca3a8d4707e2
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/77450
Reviewed-by: Daniel Hosseinian <dhoss@chromium.org>
Reviewed-by: Hui Yingst <nigi@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>
diff --git a/fpdfsdk/cpdfsdk_helpers.h b/fpdfsdk/cpdfsdk_helpers.h
index 6a0b4fc..0895ce0 100644
--- a/fpdfsdk/cpdfsdk_helpers.h
+++ b/fpdfsdk/cpdfsdk_helpers.h
@@ -19,11 +19,6 @@
 #include "core/fxcrt/fx_stream.h"
 #endif  // PDF_ENABLE_XFA
 
-#if defined(OS_WIN)
-#include <math.h>
-#include <tchar.h>
-#endif
-
 class CPDF_Annot;
 class CPDF_AnnotContext;
 class CPDF_ClipPath;
diff --git a/fpdfsdk/fpdf_text.cpp b/fpdfsdk/fpdf_text.cpp
index e6479f8..915abb9 100644
--- a/fpdfsdk/fpdf_text.cpp
+++ b/fpdfsdk/fpdf_text.cpp
@@ -22,10 +22,6 @@
 #include "third_party/base/numerics/safe_conversions.h"
 #include "third_party/base/stl_util.h"
 
-#if defined(OS_WIN)
-#include <tchar.h>
-#endif
-
 namespace {
 
 constexpr size_t kBytesPerCharacter = sizeof(unsigned short);