Fix tests that fail on FreeBSD

Author: wg

src/test/debuginfo/gdb-pretty-struct-and-enums-pre-gdb-7-7.rs

@@ -13,6 +13,7 @@
 // gdb-pretty-struct-and-enums.rs
 
 // ignore-windows failing on win32 bot
+// ignore-freebsd: gdb package too new
 // ignore-tidy-linelength
 // ignore-lldb
 // ignore-android: FIXME(#10381)

src/test/debuginfo/gdb-pretty-struct-and-enums.rs

@@ -9,6 +9,7 @@
 // except according to those terms.
 
 // ignore-windows failing on win32 bot
+// ignore-freebsd: output doesn't match
 // ignore-tidy-linelength
 // ignore-lldb
 // ignore-android: FIXME(#10381)

src/test/run-make/use-extern-for-plugins/Makefile

@@ -1,6 +1,6 @@
 -include ../tools.mk
 
-ifneq ($(UNAME),OpenBSD)
+ifneq ($(findstring BSD,$(UNAME)),BSD)
 HOST := $(shell $(RUSTC) -vV | grep 'host:' | sed 's/host: //')
 ifeq ($(findstring i686,$(HOST)),i686)
 TARGET := $(subst i686,x86_64,$(HOST))
@@ -13,6 +13,6 @@ all:
 	$(RUSTC) bar.rs -C extra-filename=-targ --target $(TARGET)
 	$(RUSTC) baz.rs --extern a=$(TMPDIR)/liba-targ.rlib --target $(TARGET)
 else
-# OpenBSD support only x86_64 architecture for now
+# FreeBSD & OpenBSD support only x86_64 architecture for now
 all:
 endif