test(windows): remove -march=native CXXFLAG

 - Users may still pass CXXFLAGS=-march=native via environment / command-line when building game / test

Author: tehhowch

.winmake

@@ -72,8 +72,6 @@ es_search_dirs ::= DIR_ESLIB="$(DIR_ESLIB)"
 scons_env ::= $(es_search_dirs) $(enable_lto)
 # Common options to pass, expanded in-recipe:
 scons_opts = -Q $(patsubst -j,,$(filter -j%,$(MAKEFLAGS))) BUILDDIR=$(BUILDDIR) BIN_DIR=$(BIN_DIR)
-# For the release target, append native architecture optimization to the user's flags.
-additional_release_cxxflags ::= "$(strip $(CXXFLAGS) -march=native)"
 
 # Configure target dependencies to invoke SCons
 dist:
@@ -83,7 +81,6 @@ release debug dist build-tests test: get_scons
 # Target-specific variable overrides
 dist: BUILDDIR ::= "$(BUILDDIR)/pkgd"
 dist: BIN_DIR ::= "$(BIN_DIR)/pkgd"
-build-tests test release: scons_env += CXXFLAGS=$(additional_release_cxxflags)
 
 # Target-specific build recipes
 dist: