build system: use -march=i686 for 32bit mingw builds

Boost is built with the same optimizations. And if they're not used then
the linker will spill annoying (but harmless) warnings about »data
section size mismatch«.

Rakefile

@@ -111,6 +111,7 @@ def setup_globals
   cflags_common           += " -Ilib/libebml -Ilib/libmatroska"                          if c?(:EBML_MATROSKA_INTERNAL)
   cflags_common           += " #{c(:MATROSKA_CFLAGS)} #{c(:EBML_CFLAGS)} #{c(:EXTRA_CFLAGS)} #{c(:DEBUG_CFLAGS)} #{c(:PROFILING_CFLAGS)} #{c(:USER_CPPFLAGS)}"
   cflags_common           += " -mno-ms-bitfields -DWINVER=0x0500 -D_WIN32_WINNT=0x0500 " if c?(:MINGW)
+  cflags_common           += " -march=i686"                                              if c?(:MINGW) && /i686/.match(c(:host))
   cflags_common           += " -fPIE "                                                   if c?(:USE_QT) && !c?(:MINGW)
   cflags_common           += " -DQT_STATICPLUGIN"                                        if c?(:USE_QT) &&  c?(:MINGW)
 

build-config.in

@@ -38,6 +38,8 @@ desktopdir = $(datadir)/applications
 mimepackagesdir = $(datadir)/mime/packages
 icondir = $(datadir)/icons/hicolor
 
+host = @host@
+
 # Common programs
 AR = @AR@
 CC = @CC@