debian packaging: disable LTO build profile

Fixes the build on Ubuntu distributions with aggressive enabling of LTO
for all builds.

This build profile sets CFLAGS and CXXFLAGS in a way that prevents cargo
tests from linking. This manifests as errors like:

= note: make[5]: *** read jobs pipe: Bad file descriptor.  Stop.
        make[5]: *** Waiting for unfinished jobs....
        lto-wrapper: fatal error: make returned 2 exit status
        compilation terminated.
        /usr/bin/ld: error: lto-wrapper failed
        collect2: error: ld returned 1 exit status

debian/rules

@@ -3,6 +3,9 @@
 
 # Uncomment this to turn on verbose mode.
 export DH_VERBOSE=1
+# The LTO profile sets CFLAGS/CXXFLAGS which confuse the compilation process; disable it
+# LTO is still performed by rustc based on Cargo.toml
+export DEB_BUILD_MAINT_OPTIONS=optimize=-lto
 
 %:
 	dh $@