misc android fixes (premake#15)

* fixed exception handling and rtti 'Off' setting
ignored warnings now auto generated additional build params as such
added support for pch (which need to take a relative path from cwd)
instead of a file located via the search path.

* added unit test for android pch

modules/android/tests/test_android_project.lua

@@ -112,3 +112,18 @@
 	<AdditionalOptions>-std=c++1z %(AdditionalOptions)</AdditionalOptions>
 ]]
 	end
+
+
+	function suite.precompiledHeader()
+		location "build"
+		pchheader "include/foo.h"
+		prepare()
+		test.capture [[
+<ClCompile>
+	<PrecompiledHeader>Use</PrecompiledHeader>
+	<PrecompiledHeaderFile>../include/foo.h</PrecompiledHeaderFile>
+	<Optimization>Disabled</Optimization>
+	<ExceptionHandling>Enabled</ExceptionHandling>
+	<RuntimeTypeInfo>true</RuntimeTypeInfo>
+]]
+	end

modules/android/vsandroid_vcxproj.lua

@@ -279,6 +279,12 @@
 		if cfg.system == p.ANDROID then
 			local opts = cfg.buildoptions
 
+			if cfg.disablewarnings and #cfg.disablewarnings > 0 then
+				for _, warning in ipairs(cfg.disablewarnings) do
+					table.insert(opts, '-Wno-'..warning)
+				end
+			end
+
 			local cpp_langmap = {
 				["C++17"]   = "-std=c++1z",
 				["gnu++17"] = "-std=gnu++1z",
@@ -315,7 +321,7 @@
 	premake.override(vc2010, "exceptionHandling", function(oldfn, cfg, condition)
 		if cfg.system == p.ANDROID then
 			-- Note: Android defaults to 'off'
-			if cfg.exceptionhandling then
+			if cfg.exceptionhandling and cfg.exceptionhandling ~= premake.OFF then
 				if _ACTION >= "vs2015" then
 					vc2010.element("ExceptionHandling", condition, "Enabled")
 				else
@@ -330,14 +336,21 @@
 	premake.override(vc2010, "runtimeTypeInfo", function(oldfn, cfg, condition)
 		if cfg.system == premake.ANDROID then
 			-- Note: Android defaults to 'off'
-			if cfg.rtti then
+			if cfg.rtti and cfg.rtti ~= premake.OFF then
 				vc2010.element("RuntimeTypeInfo", condition, "true")
 			end
 		else
 			oldfn(cfg, condition)
 		end
 	end)
 
+	premake.override(vc2010, "precompiledHeaderFile", function(oldfn, fileName, cfg)
+		if cfg.system == premake.ANDROID then
+			vc2010.element("PrecompiledHeaderFile", nil, "%s", path.rebase(fileName, cfg.basedir, cfg.location))
+		else
+			oldfn(fileName, cfg)
+		end
+	end)
 
 --
 -- Extend Link.