[Fix/hphpd] remove the trailing ';' for '=' command

Summary:
In a recent change, () were added to wrap the expression for '=', which
made ';' in the expression a syntax error. We were thinking on a general
fix but it seems hard to do without calling php parser for the command
line. This diff fixes one common benign case with traling ';', which used
to work before the () were added.

Test Plan:
make fast_tests
tried with hphpd on command line
hphpd> =123;
123

Reviewers: mwilliams, myang

Reviewed By: myang

CC: ps, mwilliams, myang, qigao

Differential Revision: 351726

Task ID: 747161

src/runtime/eval/debugger/debugger_client.cpp

@@ -1580,6 +1580,10 @@ bool DebuggerClient::processTakeCode() {
     m_code = string("<?php ") + (m_line.c_str() + 1) + ";";
     return processEval();
   } else if (first == '=') {
+    while (m_line.at(m_line.size() - 1) == ';') {
+      // strip the trailing ;
+      m_line = m_line.substr(0, m_line.size() - 1);
+    }
     m_code = string("<?php $_=(") + m_line.substr(1) + "); " + m_printFunction;
     return processEval();
   } else if (first != '<') {