mgcp_client: generate mgcp_common.h with printf

The rule in include/osmocom/mgcp_client/Makefile.am that copies
<osmocom/mgcp/mgcp_common.h> into the mgcp_client include directory
writes its banner with "echo -e". The -e option is a bash extension.
Shells whose echo follows the XSI convention expand the backslash
escapes on their own and do not take options, so -e is passed through
as the first argument to print.

The generated header then starts with

  -e /*

and every file that includes it fails to compile:

  mgcp_common.h:1:2: error: unknown type name 'e'

Measured on macOS, where /bin/sh is bash invoked as sh: the escapes are
expanded as intended, but the leading "-e " is printed literally. Any
shell with an XSI-style echo, dash among them, behaves the same way.
The build only works where /bin/sh accepts -e.

Replace it with printf and a single format string. printf is POSIX, takes
no such option, and produces the same seven lines on every shell.

Change-Id: Ibc547513745104212469ccddbc2e636c985cffe5
Signed-off-by: Andrei Gosman <andrei.gosman@gmail.com>
---
M include/osmocom/mgcp_client/Makefile.am
1 file changed, 1 insertion(+), 1 deletion(-)