Fix build with GLM 0.9.9.

This patch is an amalgamation of these upstream commits:

https://github.com/LibreOffice/core/commit/953c4add8fd76d88f49a81ae4c21a1fdcc007e57
https://github.com/LibreOffice/core/commit/5f1bf6598b5725ad1e50ae9f7ec7524cc8a834fa

diff --git a/chart2/Library_chartcore.mk b/chart2/Library_chartcore.mk
index 28bc87b89057..69d4c0552636 100644
--- a/chart2/Library_chartcore.mk
+++ b/chart2/Library_chartcore.mk
@@ -23,6 +23,12 @@ $(eval $(call gb_Library_add_defs,chartcore,\
     -DOOO_DLLIMPLEMENTATION_CHARTVIEW \
 ))
 
+ifeq ($(SYSTEM_GLM),TRUE)
+$(eval $(call gb_Library_add_defs,chartcore,\
+        -DGLM_ENABLE_EXPERIMENTAL \
+))
+endif
+
 $(eval $(call gb_Library_set_precompiled_header,chartcore,$(SRCDIR)/chart2/inc/pch/precompiled_chartcore))
 
 $(eval $(call gb_Library_use_externals,chartcore,\
diff --git a/vcl/Library_vcl.mk b/vcl/Library_vcl.mk
index c1f3cc5324e7..0b684c6185a9 100644
--- a/vcl/Library_vcl.mk
+++ b/vcl/Library_vcl.mk
@@ -49,6 +49,12 @@ $(eval $(call gb_Library_add_defs,vcl,\
 	-DENABLE_MERGELIBS=$(if $(MERGELIBS),1,0) \
 ))
 
+ifeq ($(SYSTEM_GLM),TRUE)
+$(eval $(call gb_Library_add_defs,vcl,\
+        -DGLM_ENABLE_EXPERIMENTAL \
+))
+endif
+
 $(eval $(call gb_Library_use_sdk_api,vcl))
 
 $(eval $(call gb_Library_use_custom_headers,vcl,\
diff --git a/vcl/Executable_icontest.mk b/vcl/Executable_icontest.mk
index ce163303f8a4..8c917b71cd0e 100644
--- a/vcl/Executable_icontest.mk
+++ b/vcl/Executable_icontest.mk
@@ -19,6 +19,12 @@ $(eval $(call gb_Executable_use_externals,icontest,\
 ))
 endif
 
+ifeq ($(SYSTEM_GLM),TRUE)
+$(eval $(call gb_Executable_add_defs,icontest,\
+    -DGLM_ENABLE_EXPERIMENTAL \
+))
+endif
+
 $(eval $(call gb_Executable_use_api,icontest,\
     offapi \
     udkapi \
option>
<option value='author'>author</option>
<option value='committer'>committer</option>
<option value='range'>range</option>
</select>
<input class='txt' type='search' size='10' name='q' value=''/>
<input type='submit' value='search'/>
</form>
</td></tr></table>
<div class='path'>path: <a href='/guix/log/?id=cda7f4bc8ecf331d623c7d37b01931a46830c648'>root</a>/<a href='/guix/log/gnu?id=cda7f4bc8ecf331d623c7d37b01931a46830c648'>gnu</a>/<a href='/guix/log/gnu/packages?id=cda7f4bc8ecf331d623c7d37b01931a46830c648'>packages</a>/<a href='/guix/log/gnu/packages/gobby.scm?id=cda7f4bc8ecf331d623c7d37b01931a46830c648'>gobby.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/packages/gobby.scm?id=cda7f4bc8ecf331d623c7d37b01931a46830c648&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2017-08-20 11:30:43 +0200'>2017-08-20</span></td><td><a href='/guix/commit/gnu/packages/gobby.scm?id=50631fe933037977cf54140d0cd473cea9ea1994'>gnu: gobby: Re-add Gobby 0.4.</a><span class='msg-avail'>...</span></td><td>Andy Wingo</td></tr>
<tr><td><span title='2017-08-20 10:52:56 +0530'>2017-08-20</span></td><td><a href='/guix/commit/gnu/packages/gobby.scm?id=97291c0c7c6bc50aa503f9bf7f9abd97cffae9c9'>gnu: gobby: Update to 0.5.0.</a><span class='msg-avail'>...</span></td><td>Arun Isaac</td></tr>
<tr><td><span title='2017-08-20 10:52:55 +0530'>2017-08-20</span></td><td><a href='/guix/commit/gnu/packages/gobby.scm?id=6a84ec8eb3e58f22e2961016722ae01e464cb8f4'>gnu: Add libinfinity.</a><span class='msg-avail'>...</span></td><td>Arun Isaac</td></tr>
<tr><td><span title='2016-09-27 14:46:10 +0200'>2016-09-27</span></td><td><a href='/guix/commit/gnu/packages/gobby.scm?id=e9070933bfe23412fce21237c51c6d2d86cb8681'>gnu: Add gobby.</a><span class='msg-avail'>...</span></td><td>Andy Wingo</td></tr>
<tr><td><span title='2016-09-27 14:46:10 +0200'>2016-09-27</span></td><td><a href='/guix/commit/gnu/packages/gobby.scm?id=22a3cff3c81d58c9d7d80c8beebec680ee90d9c3'>gnu: Add obby.</a><span class='msg-avail'>...</span></td><td>Andy Wingo</td></tr>
<tr><td><span title='2016-09-27 14:46:10 +0200'>2016-09-27</span></td><td><a href='/guix/commit/gnu/packages/gobby.scm?id=c8105e811b1f3a1f01d6942bd9ddeb8004ce30f3'>gnu: Add libnet6.</a><span class='msg-avail'>...</span></td><td>Andy Wingo</td></tr>