[Piglit] [PATCH v2] README: correct flags for 32-on-64 build

[Constantine Charlamov]

So far this is the only options I found to build 32-on-64. It supersedes
the prev. patch to README — turns out, replacing i386→x86 isn't enough.
The inconsistent results were because cmake retains options used for old
runs. This patch was tested by completely removing piglit, and git
cloning it again.

v2: (per Brian Paul comment) fix typos, and mention that it's enough
to remove CMakeCache.txt from the previous build.

Signed-off-by: Constantine Charlamov <Hi-Angel at yandex.ru>
Supersedes: https://patchwork.freedesktop.org/patch/141700/
---
 README | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/README b/README
index 23ae46352..43bdfcae7 100644
--- a/README
+++ b/README
@@ -88,8 +88,10 @@ Now build everything:
 2.1 Cross Compiling
 -------------------
 
-On Linux, if cross-compiling a 32-bit build on a 64-bit host, then you must
-invoke cmake with option "-DCMAKE_SYSTEM_PROCESSOR=i386".
+On Linux, if cross-compiling a 32-bit build on a 64-bit host, first make sure
+you didn't have CMakeCache.txt file left from 64-bit build (it would retain old
+flags), then you must invoke cmake with options "-DCMAKE_SYSTEM_PROCESSOR=x86
+-DCMAKE_C_FLAGS=-m32 -DCMAKE_CXX_FLAGS=-m32".
 
 
 2.2 Ubuntu
-- 
2.11.1