Enforce x64 compiler in native NMAKE builds (#780)

Add /options:strict and /favor:AMD64 to CL_OPTS so that if an x86
cl.exe is on the PATH (e.g. from stale MSBuild node reuse), the build
fails immediately with error D8043 instead of silently producing x86
binaries.

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: jasonleenaylor

Bld/_init.mak

@@ -174,7 +174,7 @@ CL_OPTS=$(CL_OPTS) /MD
 # JohnT: /EHa is required so that our code that converts C exceptions (access violation, div by zero)
 # into C++ ThrowableSd exceptions, and catches them at interface boundaries, can work
 # reliably. The October 1999 edition of Bugslayer in MSDN has a fuller explanation.
-CL_OPTS=$(CL_OPTS) /W4 /WX /Fd"$(INT_DIR)/" /EHa /GR /GF /Zm400 /D_WIN32_WINNT=0x0500
+CL_OPTS=$(CL_OPTS) /options:strict /favor:AMD64 /W4 /WX /Fd"$(INT_DIR)/" /EHa /GR /GF /Zm400 /D_WIN32_WINNT=0x0500
 
 PREPROCESS_OPTS=/E
 

Lib/src/graphite2/graphite2.mak

@@ -22,7 +22,7 @@ GR2_LIB=$(OUT_DIR)\graphite2.lib
 INCLUDE=$(INCLUDE);$(GR2_SRC);$(GR2_INC)
 
 DEFS=/DGRAPHITE2_STATIC /DWIN32
-CL_OPTS=/EHsc /Zi
+CL_OPTS=/options:strict /EHsc /WX /Zi /favor:AMD64
 
 !IF "$(BUILD_TYPE)"=="d"
 CL_OPTS=$(CL_OPTS) /MDd /Od