Adjust i686 patch to apply more accurately

The --with-arch=pentium4 keeps going under winpthreads because of the
matching context, which effectively disables it. One solution would be
to increase the context and deal with the extra conflicts. Instead
change the context so it doesn't match in the wrong place.

src/variant-i686.patch

@@ -15,10 +15,10 @@
 +RUN echo >/gcc-$GCC_VERSION/gcc/config/i386/winnt-utf8.manifest
 +
  WORKDIR /x-gcc
-@@ -104,2 +108,3 @@ RUN /gcc-$GCC_VERSION/configure \
-         --target=$ARCH \
+@@ -103,2 +107,3 @@ RUN /gcc-$GCC_VERSION/configure \
+         --with-sysroot=/bootstrap \
 +        --with-arch=pentium4 \
-         --enable-static \
+         --target=$ARCH \
 @@ -132,4 +137,4 @@ RUN /mingw-w64-v$MINGW_VERSION/mingw-w64-crt/configure \
          --disable-dependency-tracking \
 -        --disable-lib32 \
@@ -37,7 +37,7 @@
 +        --enable-lib32 \
 +        --disable-lib64 \
          CFLAGS="-Os" \
-@@ -239,2 +245,3 @@ RUN /mingw-w64-v$MINGW_VERSION/mingw-w64-libraries/winpthreads/configure \
-         --host=$ARCH \
+@@ -251,2 +257,3 @@ RUN /gcc-$GCC_VERSION/configure \
+         --with-native-system-header-dir=/include \
 +        --with-arch=pentium4 \
-         --enable-static \
+         --target=$ARCH \