Bug#1010507: openmsx-debugger: ftbfs on riscv64

[Bo YU <tsu.yubo@gmail.com>]

Source: openmsx-debugger
Version: 0.1~git20200913-1
Severity: normal
Tags: ftbfs patch
User: debian-riscv@lists.debian.org
Usertags: riscv64
X-Debbugs-Cc: debian-riscv@lists.debian.org

Dear Maintainer,

The openmsx-debugger has a ftbfs issue on riscv64:

```
make[1]: Entering directory '/<<PKGBUILDDIR>>'
/usr/bin/make DEB_CXXFLAGS="" \
DEB_COMPILE_FLAGS="-Wdate-time -D_FORTIFY_SOURCE=2 \
-g -O2 -ffile-prefix-map=/<<PKGBUILDDIR>>=. -fstack-protector-strong -Wformat -Werror=format-security" \
DEB_LINK_FLAGS="-Wl,-z,relro"
make[2]: Entering directory '/<<PKGBUILDDIR>>'
echo "Autodetecting native system:"
Autodetecting native system:
mkdir -p derived/detectsys
python3 build/detectsys.py > derived/detectsys/detectsys.mk
Using Python 3.9.2 native system detection...
Unsupported or unrecognised CPU "riscv64"
make[2]: Nothing to be done for 'default'.
make[2]: Leaving directory '/<<PKGBUILDDIR>>'
# Remove rpath.
chrpath -d derived/bin/openmsx-debugger
open: No such file or directory
elf_open: Invalid argument
make[1]: *** [debian/rules:11: override_dh_auto_build] Error 1
make[1]: Leaving directory '/<<PKGBUILDDIR>>'
make: *** [debian/rules:6: build-arch] Error 2
dpkg-buildpackage: error: debian/rules build-arch subprocess returned exit status 2
...
```

The full buildd log is:

https://buildd.debian.org/status/fetch.php?pkg=openmsx-debugger&arch=riscv64&ver=0.1%7Egit20200913-1&stamp=1621673138&raw=0

I have tested attach patch and it is ok to build on riscv64 real hardware.

BR,
Bo

fix ftbfs issue on riscv64

Bo YU <tsu.yubo@gmail.com>
--- a/build/detectsys.py
+++ b/build/detectsys.py
@@ -45,6 +45,8 @@
 		return 'sheb' if cpu.endswith('eb') else 'sh'
 	elif cpu == 'avr32':
 		return 'avr32'
+	elif cpu == 'riscv64':
+		return 'riscv64'
 	elif cpu == '':
 		# Python couldn't figure it out.
 		os = system().lower()