Intel ISAL requires yasm version 1.2.0 > with AVX2 instruction support, document it!

BUILDDEPS.md

@@ -7,6 +7,9 @@ $ sudo apt-get install git build-essential
 ```
 
 ##### Install YASM
+
+Minio depends on Intel ISAL library for erasure coding, ISAL uses Intel AVX2 processor instructions, to compile these files one needs to install ``yasm`` which supports AVX2 instructions. AVX2 support only ended in ``yasm`` from version ``1.2.0``, any version below ``1.2.0`` will throw a build error as referenced in issue [here](https://github.com/Minio-io/minio/issues/163)
+
 ```sh
 $ sudo apt-get install yasm
 ```

checkdeps.sh

@@ -42,7 +42,7 @@ if [ $? -ne 0 ]; then
 fi
 
 if ! yasm -f elf64 -i isal/include isal/src/gf-vect-dot-prod-avx2.asm -o /dev/null 2>/dev/null ; then
-    MISSING="${MISSING} yasm(elf64 support)"
+    MISSING="${MISSING} yasm(1.2.0)"
 fi
 
 ## If dependencies are missing, warn the user and abort
@@ -54,7 +54,7 @@ if [ "x${MISSING}" != "x" ]; then
   echo "** ${MISSING} **"
   echo
   echo "Please install them "
-  echo "$ sudo apt-get install ${MISSING}"
+  echo "${MISSING}"
   echo
   exit 1
 fi