swiftMSVCRT: build with -Xcc -D_USE_MATH_DEFINES

This enables the use of the math defines when building tgmath.swift.
Although not used in the normal branch, this define is necessary to
build the swiftMSVCRT module for TensorFlow which uses the math
constants.

Author: compnerd

stdlib/public/Platform/CMakeLists.txt

@@ -22,7 +22,10 @@ add_swift_target_library(swiftDarwin ${SWIFT_STDLIB_LIBRARY_BUILD_TYPES} IS_SDK_
       ${swift_platform_gyb_sources}
       Darwin.swift.gyb
 
-    SWIFT_COMPILE_FLAGS -Xfrontend -disable-objc-attr-requires-foundation-module ${SWIFT_RUNTIME_SWIFT_COMPILE_FLAGS} ${SWIFT_STANDARD_LIBRARY_SWIFT_FLAGS}
+    SWIFT_COMPILE_FLAGS
+      ${SWIFT_RUNTIME_SWIFT_COMPILE_FLAGS}
+      ${SWIFT_STANDARD_LIBRARY_SWIFT_FLAGS}
+      -Xfrontend -disable-objc-attr-requires-foundation-module
     LINK_FLAGS "${SWIFT_RUNTIME_SWIFT_LINK_FLAGS}"
     TARGET_SDKS ALL_APPLE_PLATFORMS
     INSTALL_IN_COMPONENT sdk-overlay
@@ -37,7 +40,9 @@ add_swift_target_library(swiftGlibc ${SWIFT_STDLIB_LIBRARY_BUILD_TYPES} IS_SDK_O
       ${swift_platform_gyb_sources}
       Glibc.swift.gyb
 
-    SWIFT_COMPILE_FLAGS ${SWIFT_RUNTIME_SWIFT_COMPILE_FLAGS} ${SWIFT_STANDARD_LIBRARY_SWIFT_FLAGS}
+    SWIFT_COMPILE_FLAGS
+      ${SWIFT_RUNTIME_SWIFT_COMPILE_FLAGS}
+      ${SWIFT_STANDARD_LIBRARY_SWIFT_FLAGS}
     LINK_FLAGS "${SWIFT_RUNTIME_SWIFT_LINK_FLAGS}"
     TARGET_SDKS ANDROID CYGWIN FREEBSD LINUX HAIKU
     INSTALL_IN_COMPONENT sdk-overlay
@@ -51,7 +56,10 @@ add_swift_target_library(swiftMSVCRT ${SWIFT_STDLIB_LIBRARY_BUILD_TYPES} IS_SDK_
     GYB_SOURCES
       ${swift_platform_gyb_sources}
 
-    SWIFT_COMPILE_FLAGS ${SWIFT_RUNTIME_SWIFT_COMPILE_FLAGS} ${SWIFT_STANDARD_LIBRARY_SWIFT_FLAGS}
+    SWIFT_COMPILE_FLAGS
+      ${SWIFT_RUNTIME_SWIFT_COMPILE_FLAGS}
+      ${SWIFT_STANDARD_LIBRARY_SWIFT_FLAGS}
+      -Xcc -D_USE_MATH_DEFINES
     LINK_FLAGS "${SWIFT_RUNTIME_SWIFT_LINK_FLAGS}"
     TARGET_SDKS WINDOWS
     INSTALL_IN_COMPONENT sdk-overlay)