Add longPathAware manifest to enable long paths on Windows

Fixes: ninja-build#1900

CMakeLists.txt

@@ -171,6 +171,10 @@ if(NINJA_BUILD_BINARY)
 	endif()
 endif()
 
+if (MSVC)
+  target_sources(ninja PRIVATE src/longpath.manifest)
+endif()
+
 # Adds browse mode into the ninja binary if it's supported by the host platform.
 if(platform_supports_ninja_browse)
 	# Inlines src/browse.py into the browse_py.h header, so that it can be included

src/longpath.manifest

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0">
+<application  xmlns="urn:schemas-microsoft-com:asm.v3">
+    <windowsSettings xmlns:ws2="http://schemas.microsoft.com/SMI/2016/WindowsSettings">
+        <ws2:longPathAware>true</ws2:longPathAware>
+    </windowsSettings>
+</application>
+</assembly>