Move ucrt rule, add to gitignore

Author: andrjohns

.gitignore

@@ -71,6 +71,7 @@ lib/tbb
 
 # local make include
 /make/local
+/make/ucrt
 
 # python byte code
 *.pyc

make/compiler_flags

@@ -121,15 +121,6 @@ CXXFLAGS_LANG ?= -std=c++1y
 CXXFLAGS_SUNDIALS ?= -pipe $(CXXFLAGS_OPTIM_SUNDIALS) $(CPPFLAGS_FLTO_SUNDIALS)
 #CXXFLAGS_GTEST
 
-make/ucrt:
-  pound := \#
-  UCRT_STRING := $(shell echo '$(pound)include <windows.h>' | $(CXX) -E -dM -  | findstr _UCRT)
-  ifneq (,$(UCRT_STRING))
-    IS_UCRT ?= true
-  else
-    IS_UCRT ?= false
-  endif
-  $(shell echo "IS_UCRT ?= $(IS_UCRT)" > $(MATH)make/ucrt)
 
 ## These are the other compiler flags that can be set.
 ##
@@ -170,6 +161,16 @@ ifeq ($(OS),Windows_NT)
     CXXFLAGS_OS ?= -m64
   endif
 
+  make/ucrt:
+    pound := \#
+    UCRT_STRING := $(shell echo '$(pound)include <windows.h>' | $(CXX) -E -dM -  | findstr _UCRT)
+    ifneq (,$(UCRT_STRING))
+      IS_UCRT ?= true
+    else
+      IS_UCRT ?= false
+    endif
+    $(shell echo "IS_UCRT ?= $(IS_UCRT)" > $(MATH)make/ucrt)
+
   include make/ucrt
   ifeq ($(IS_UCRT),true)
     CXXFLAGS_OS += -D_UCRT