Document I-invalid-cmake-usage buildd tag in POD.

diff --git a/bin/blhc b/bin/blhc
index 70f814d954826ec36842c083e9df173eb195ac68..79b72f51bc5941b096e0531e82890bb32abe6292 100755 (executable)
--- a/bin/blhc
+++ b/bin/blhc
@@ -1155,6 +1155,13 @@ CPPFLAGS, CFLAGS, CXXFLAGS, LDFLAGS missing.
 
 =item B<I-invalid-cmake-used> (version)
 
+By default CMake ignores CPPFLAGS thus missing those hardening flags. Debian
+patched CMake in versions 2.8.7-1 and 2.8.7-2 to respect CPPFLAGS, but this
+patch was rejected by upstream and later reverted in Debian. Thus those two
+versions show correct usage of CPPFLAGS even if the package doesn't correctly
+handle them (for example by passing them to CFLAGS). To prevent false
+negatives just blacklist those two versions.
+
 =item B<I-no-compiler-commands>
 
 No compiler commands were detected. Either the log contains none or they were