build, tools, win: add nasm detection for OpenSSL

OpenSSL-1.1.0 requires the nasm assembler for building asm files on
Windows. This finds nasm at \Program Files\NASM\nasm.exe or
\ProgramFiles(x86)\NASM\nasm.exe in vcbuild.bat for users who did not
add its path in their enviroments.

Fixes: nodejs/build#1190

Author: joaocgreis

BUILDING.md

@@ -258,6 +258,9 @@ Prerequisites:
 * Basic Unix tools required for some tests,
   [Git for Windows](http://git-scm.com/download/win) includes Git Bash
   and tools which can be included in the global `PATH`.
+* **Optional** (for OpenSSL assembler modules): the [NetWide Assembler](http://www.nasm.us/),
+  if not installed in the default location it needs to be manually added
+  to `PATH`.
 * **Optional** (to build the MSI): the [WiX Toolset v3.11](http://wixtoolset.org/releases/)
   and the [Wix Toolset Visual Studio 2017 Extension](https://marketplace.visualstudio.com/items?itemName=RobMensching.WixToolsetVisualStudio2017Extension).
 

tools/msvs/find_nasm.cmd

@@ -0,0 +1,19 @@
+@IF NOT DEFINED DEBUG_HELPER @ECHO OFF
+
+ECHO Looking for NASM
+
+FOR /F "delims=" %%a IN ('where nasm 2^> NUL') DO (
+  EXIT /B 0
+)
+
+IF EXIST "%ProgramFiles%\NASM\nasm.exe" (
+  SET "Path=%Path%;%ProgramFiles%\NASM"
+  EXIT /B 0
+)
+
+IF EXIST "%ProgramFiles(x86)%\NASM\nasm.exe" (
+  SET "Path=%Path%;%ProgramFiles(x86)%\NASM"
+  EXIT /B 0
+)
+
+EXIT /B 1

vcbuild.bat

@@ -168,6 +168,9 @@ if "%target%"=="Clean" rmdir /S /Q %~dp0deps\icu
 call tools\msvs\find_python.cmd
 if errorlevel 1 goto :exit
 
+call tools\msvs\find_nasm.cmd
+if errorlevel 1 echo Could not find NASM, it will not be used.
+
 call :getnodeversion || exit /b 1
 
 if defined TAG set configure_flags=%configure_flags% --tag=%TAG%