testsuite: Fix cc-with-tweaks.sh being executed in the wrong shell

The cc-with-tweaks.sh script needs to be executed with bash.  When
trying to run this:

  make check RUNTESTFLAGS="--target_board=dwarf4-gdb-index" TESTS="gdb.base/return.exp"

I get:

  gdb compile failed, /home/emaisin/src/binutils-gdb/gdb/contrib/cc-with-tweaks.sh: 174: /home/emaisin/src/binutils-gdb/gdb/contrib/cc-with-tweaks.sh: Bad substitution

The reason is that the board files execute cc-with-tweaks.sh using
/bin/sh, which points to dash on my machine.  Remove the /bin/sh part
and let the shebang choose the right interpreter.

gdb/testsuite/ChangeLog:

	* boards/cc-with-tweaks.exp: Don't call cc-with-tweaks.sh
	through /bin/sh.
	* boards/dwarf4-gdb-index.exp: Likewise.
	* boards/fission-dwp.exp: Likewise.

4 files changed, 13 insertions, 6 deletions

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index df218ef..79909ae 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,10 @@
+2018-06-20  Simon Marchi  <simon.marchi@ericsson.com>
+
+	* boards/cc-with-tweaks.exp: Don't call cc-with-tweaks.sh
+	through /bin/sh.
+	* boards/dwarf4-gdb-index.exp: Likewise.
+	* boards/fission-dwp.exp: Likewise.
+
 2018-06-20  Ulrich Weigand  <uweigand@de.ibm.com>
 
 	* gdb.base/float128.exp: Add comment and improved fail message
diff --git a/gdb/testsuite/boards/cc-with-tweaks.exp b/gdb/testsuite/boards/cc-with-tweaks.exp
index 7f94142..1758e24 100644
--- a/gdb/testsuite/boards/cc-with-tweaks.exp
+++ b/gdb/testsuite/boards/cc-with-tweaks.exp
@@ -44,8 +44,8 @@ set contrib_dir [file normalize $srcdir/../contrib]
 if ![info exists CC_FOR_TARGET] {
     set CC_FOR_TARGET "$found_gcc"
 }
-set CC_FOR_TARGET "/bin/sh $contrib_dir/cc-with-tweaks.sh $CC_WITH_TWEAKS_FLAGS $CC_FOR_TARGET"
+set CC_FOR_TARGET "$contrib_dir/cc-with-tweaks.sh $CC_WITH_TWEAKS_FLAGS $CC_FOR_TARGET"
 if ![info exists CXX_FOR_TARGET] {
     set CXX_FOR_TARGET "$found_gxx"
 }
-set CXX_FOR_TARGET "/bin/sh $contrib_dir/cc-with-tweaks.sh $CC_WITH_TWEAKS_FLAGS $CXX_FOR_TARGET"
+set CXX_FOR_TARGET "$contrib_dir/cc-with-tweaks.sh $CC_WITH_TWEAKS_FLAGS $CXX_FOR_TARGET"
diff --git a/gdb/testsuite/boards/dwarf4-gdb-index.exp b/gdb/testsuite/boards/dwarf4-gdb-index.exp
index 81bffbd..6e02141 100644
--- a/gdb/testsuite/boards/dwarf4-gdb-index.exp
+++ b/gdb/testsuite/boards/dwarf4-gdb-index.exp
@@ -36,8 +36,8 @@ set contrib_dir [file normalize $srcdir/../contrib]
 if ![info exists CC_FOR_TARGET] {
     set CC_FOR_TARGET "$found_gcc"
 }
-set CC_FOR_TARGET "/bin/sh $contrib_dir/cc-with-tweaks.sh -i $CC_FOR_TARGET"
+set CC_FOR_TARGET "$contrib_dir/cc-with-tweaks.sh -i $CC_FOR_TARGET"
 if ![info exists CXX_FOR_TARGET] {
     set CXX_FOR_TARGET "$found_gxx"
 }
-set CXX_FOR_TARGET "/bin/sh $contrib_dir/cc-with-tweaks.sh -i $CXX_FOR_TARGET"
+set CXX_FOR_TARGET "$contrib_dir/cc-with-tweaks.sh -i $CXX_FOR_TARGET"
diff --git a/gdb/testsuite/boards/fission-dwp.exp b/gdb/testsuite/boards/fission-dwp.exp
index 0414981..82a0253 100644
--- a/gdb/testsuite/boards/fission-dwp.exp
+++ b/gdb/testsuite/boards/fission-dwp.exp
@@ -30,11 +30,11 @@ set contrib_dir [file normalize $srcdir/../contrib]
 if ![info exists CC_FOR_TARGET] {
     set CC_FOR_TARGET "$found_gcc"
 }
-set CC_FOR_TARGET "/bin/sh $contrib_dir/cc-with-tweaks.sh -p $CC_FOR_TARGET"
+set CC_FOR_TARGET "$contrib_dir/cc-with-tweaks.sh -p $CC_FOR_TARGET"
 if ![info exists CXX_FOR_TARGET] {
     set CXX_FOR_TARGET "$found_gxx"
 }
-set CXX_FOR_TARGET "/bin/sh $contrib_dir/cc-with-tweaks.sh -p $CXX_FOR_TARGET"
+set CXX_FOR_TARGET "$contrib_dir/cc-with-tweaks.sh -p $CXX_FOR_TARGET"
 
 if ![info exists READELF_FOR_TARGET] {
     set READELF_FOR_TARGET "[transform readelf]"