drop superfluous call of headers_check

headers_check is run twice when building the kernel rpms.

CONFIG_HEADERS_CHECK is already set to "y" in config-generic. But there
are also a few lines in kernel.spec where headers_check is invoked again.

Also

    grep -q exist hdrwarnings.txt

will never match as errors aren't redirected to hdrwarnings.txt

kernel.spec

@@ -1824,15 +1824,6 @@ cd linux-%{KVERREL}
 # Install kernel headers
 make ARCH=%{hdrarch} INSTALL_HDR_PATH=$RPM_BUILD_ROOT/usr headers_install
 
-# Do headers_check but don't die if it fails.
-make ARCH=%{hdrarch} INSTALL_HDR_PATH=$RPM_BUILD_ROOT/usr headers_check \
-     > hdrwarnings.txt || :
-if grep -q exist hdrwarnings.txt; then
-   sed s:^$RPM_BUILD_ROOT/usr/include/:: hdrwarnings.txt
-   # Temporarily cause a build failure if header inconsistencies.
-   # exit 1
-fi
-
 find $RPM_BUILD_ROOT/usr/include \
      \( -name .install -o -name .check -o \
      	-name ..install.cmd -o -name ..check.cmd \) | xargs rm -f