scons: Define _USE_MATH_DEFINES on MSVC.
diff --git a/scons/gallium.py b/scons/gallium.py
index 34877b2..a6d69fd 100644
--- a/scons/gallium.py
+++ b/scons/gallium.py
@@ -263,6 +263,7 @@
         if msvc and env['toolchain'] != 'winddk':
             cppdefines += [
                 'VC_EXTRALEAN',
+                '_USE_MATH_DEFINES',
                 '_CRT_SECURE_NO_WARNINGS',
                 '_CRT_SECURE_NO_DEPRECATE',
                 '_SCL_SECURE_NO_WARNINGS',
diff --git a/scons/generic.py b/scons/generic.py
index a9c2244..a3b73b0 100644
--- a/scons/generic.py
+++ b/scons/generic.py
@@ -335,7 +335,11 @@
         if msvc:
             cppdefines += [
                 'VC_EXTRALEAN',
+                '_USE_MATH_DEFINES',
+                '_CRT_SECURE_NO_WARNINGS',
                 '_CRT_SECURE_NO_DEPRECATE',
+                '_SCL_SECURE_NO_WARNINGS',
+                '_SCL_SECURE_NO_DEPRECATE',
             ]
         if debug:
             cppdefines += ['_DEBUG']