Build failure when using --disable-backend-(flint|brass)

[jbergstroem]

libtool: link: x86_64-pc-linux-gnu-g++ -Wall -W -Wredundant-decls -Wpointer-arith -Wcast-qual -Wcast-align -Wno-long-long -Wformat-security -fno-gnu-keywords -Wundef -Woverloaded-virtual -Wstrict-null-sentinel -Wshadow -Wstrict-overflow=1 -Winit-self -Wlogical-op -Wmissing-declarations -fvisibility=hidden -g -O2 -o bin/.libs/xapian-inspect bin/bin_xapian_inspect-xapian-inspect.o  ./.libs/libgetopt.a ./.libs/libxapian.so -lz -luuid -Wl,-rpath -Wl,/usr/lib64
libtool: link: x86_64-pc-linux-gnu-g++ -Wall -W -Wredundant-decls -Wpointer-arith -Wcast-qual -Wcast-align -Wno-long-long -Wformat-security -fno-gnu-keywords -Wundef -Woverloaded-virtual -Wstrict-null-sentinel -Wshadow -Wstrict-overflow=1 -Winit-self -Wlogical-op -Wmissing-declarations -fvisibility=hidden -g -O2 -o bin/.libs/xapian-replicate bin/xapian-replicate.o  ./.libs/libgetopt.a ./.libs/libxapian.so -lz -luuid -Wl,-rpath -Wl,/usr/lib64
bin/bin_xapian_inspect-xapian-inspect.o: In function `do_until':
/home/jbergstroem/xapian-core-1.2.7/bin/xapian-inspect.cc:108: undefined reference to `FlintCursor::next()'
/home/jbergstroem/xapian-core-1.2.7/bin/xapian-inspect.cc:121: undefined reference to `FlintCursor::read_tag(bool)'
/home/jbergstroem/xapian-core-1.2.7/bin/xapian-inspect.cc:108: undefined reference to `FlintCursor::next()'
/home/jbergstroem/xapian-core-1.2.7/bin/xapian-inspect.cc:121: undefined reference to `FlintCursor::read_tag(bool)'
bin/bin_xapian_inspect-xapian-inspect.o: In function `main':
/home/jbergstroem/xapian-core-1.2.7/bin/xapian-inspect.cc:179: undefined reference to `FlintTable::FlintTable(char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, bool, int, bool)'
/home/jbergstroem/xapian-core-1.2.7/bin/xapian-inspect.cc:180: undefined reference to `FlintTable::open()'
/home/jbergstroem/xapian-core-1.2.7/bin/xapian-inspect.cc:186: undefined reference to `FlintCursor::FlintCursor(FlintTable*)'
/home/jbergstroem/xapian-core-1.2.7/bin/xapian-inspect.cc:187: undefined reference to `FlintCursor::find_entry(std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)'
/home/jbergstroem/xapian-core-1.2.7/bin/xapian-inspect.cc:188: undefined reference to `FlintCursor::next()'
/home/jbergstroem/xapian-core-1.2.7/bin/xapian-inspect.cc:194: undefined reference to `FlintCursor::read_tag(bool)'
/home/jbergstroem/xapian-core-1.2.7/bin/xapian-inspect.cc:216: undefined reference to `FlintCursor::find_entry(std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)'
/home/jbergstroem/xapian-core-1.2.7/bin/xapian-inspect.cc:217: undefined reference to `FlintCursor::prev()'
/home/jbergstroem/xapian-core-1.2.7/bin/xapian-inspect.cc:208: undefined reference to `FlintCursor::next()'
/home/jbergstroem/xapian-core-1.2.7/bin/xapian-inspect.cc:186: undefined reference to `FlintCursor::~FlintCursor()'
/home/jbergstroem/xapian-core-1.2.7/bin/xapian-inspect.cc:179: undefined reference to `FlintTable::~FlintTable()'
bin/bin_xapian_inspect-xapian-inspect.o: In function `FlintTable::empty() const':
/home/jbergstroem/xapian-core-1.2.7/./backends/flint/flint_table.h:546: undefined reference to `FlintTable::really_empty() const'
bin/bin_xapian_inspect-xapian-inspect.o: In function `main':
/home/jbergstroem/xapian-core-1.2.7/bin/xapian-inspect.cc:232: undefined reference to `FlintCursor::find_entry(std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)'
/home/jbergstroem/xapian-core-1.2.7/bin/xapian-inspect.cc:237: undefined reference to `FlintCursor::find_entry(std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)'
/home/jbergstroem/xapian-core-1.2.7/bin/xapian-inspect.cc:186: undefined reference to `FlintCursor::~FlintCursor()'
/home/jbergstroem/xapian-core-1.2.7/bin/xapian-inspect.cc:179: undefined reference to `FlintTable::~FlintTable()'
/home/jbergstroem/xapian-core-1.2.7/bin/xapian-inspect.cc:186: undefined reference to `FlintCursor::~FlintCursor()'
/home/jbergstroem/xapian-core-1.2.7/bin/xapian-inspect.cc:179: undefined reference to `FlintTable::~FlintTable()'
bin/bin_xapian_inspect-xapian-inspect.o: In function `do_until':
/home/jbergstroem/xapian-core-1.2.7/bin/xapian-inspect.cc:114: undefined reference to `FlintCursor::prev()'
collect2: ld returned 1 exit status
make[2]: *** [bin/xapian-inspect] Error 1
make[2]: *** Waiting for unfinished jobs....
make[2]: Leaving directory `/home/jbergstroem/xapian-core-1.2.7'
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory `/home/jbergstroem/xapian-core-1.2.7'
make: *** [all] Error 2

[jbergstroem]

Duplicate of #603 which has more information about this issue.