qemu-iotests: convert `pwd` and $(pwd) to $PWD

POSIX requires $PWD to be reliable, and we expect all
shells used by qemu scripts to be relatively close to
POSIX.  Thus, it is smarter to avoid forking the pwd
executable for something that is already available in
the environment.

So replace it with the following:

sed -i 's/\(`pwd`\|\$(pwd)\)/$PWD/g' $(git grep -l pwd)

Then delete a pointless line assigning PWD to itself.

Cc: kwolf@redhat.com
Cc: mreitz@redhat.com
Cc: eblake@redhat.com
Suggested-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Mao Zhongyi <maozhongyi@cmss.chinamobile.com>
Message-Id: <20181024094051.4470-2-maozhongyi@cmss.chinamobile.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
[eblake: touch up commit message, reorder series, tweak a couple more files]
Signed-off-by: Eric Blake <eblake@redhat.com>

configure

@@ -878,7 +878,7 @@ Linux)
   vhost_crypto="yes"
   vhost_scsi="yes"
   vhost_vsock="yes"
-  QEMU_INCLUDES="-I\$(SRC_PATH)/linux-headers -I$(pwd)/linux-headers $QEMU_INCLUDES"
+  QEMU_INCLUDES="-I\$(SRC_PATH)/linux-headers -I$PWD/linux-headers $QEMU_INCLUDES"
   supported_os="yes"
   libudev="yes"
 ;;

scripts/coccinelle/tcg_gen_extract.cocci

@@ -17,7 +17,7 @@
 //     --keep-comments --in-place \
 //     --use-gitgrep --dir target
 //
-// $ docker run --rm -v `pwd`:`pwd` -w `pwd` philmd/coccinelle \
+// $ docker run --rm -v $PWD:$PWD -w $PWD philmd/coccinelle \
 //     --macro-file scripts/cocci-macro-file.h \
 //     --sp-file scripts/coccinelle/tcg_gen_extract.cocci \
 //     --keep-comments --in-place \

tests/check-block.sh

@@ -5,9 +5,9 @@ if [ "$#" -ne 0 ]; then
     FORMAT_LIST="$@"
 fi
 
-export QEMU_PROG="$(pwd)/x86_64-softmmu/qemu-system-x86_64"
-export QEMU_IMG_PROG="$(pwd)/qemu-img"
-export QEMU_IO_PROG="$(pwd)/qemu-io"
+export QEMU_PROG="$PWD/x86_64-softmmu/qemu-system-x86_64"
+export QEMU_IMG_PROG="$PWD/qemu-img"
+export QEMU_IO_PROG="$PWD/qemu-io"
 
 if [ ! -x $QEMU_PROG ]; then
     echo "'make check-block' requires qemu-system-x86_64"

tests/qemu-iotests/check

@@ -99,7 +99,7 @@ set_prog_path()
 }
 
 if [ -z "$TEST_DIR" ]; then
-        TEST_DIR=`pwd`/scratch
+        TEST_DIR=$PWD/scratch
 fi
 
 if [ ! -e "$TEST_DIR" ]; then

tests/qemu-iotests/common.config

@@ -25,8 +25,6 @@ HOSTOS=`uname -s`
 arch=`uname -m`
 [[ "$arch" =~ "ppc64" ]] && qemu_arch=ppc64 || qemu_arch="$arch"
 
-export PWD=`pwd`
-
 # make sure we have a standard umask
 umask 022
 

tests/qemu-iotests/common.rc

@@ -160,7 +160,7 @@ fi
 ORIG_TEST_IMG="$TEST_IMG"
 
 if [ -z "$TEST_DIR" ]; then
-        TEST_DIR=`pwd`/scratch
+        TEST_DIR=$PWD/scratch
 fi
 
 QEMU_TEST_DIR="${TEST_DIR}"